When changing an existing node environment variable (%JENKINS_BUILD_REPOSITORY%) value in the node's configuration dialog, the change is not applied. Looking at the systemInfo of the node shows, that the variable still has got the old value. Also reloading the Jenkins configuration from disk did not help.
The only thing that seems to help is a reboot of the jenkins server. Restarting the slave isn't enough.
Here is some more detail from the developers using Jenkins for their builds.
I know you should only have to restart the Jenkins slave service and know how to do that. I’ve tried that. I’ve also tried rebooting the machine, which also restarts the Jenkins slave service. Same result.

I’ve checked the environment variables on our build server (BOSBLD-TEAM6):
JENKINS_BUILD_REPOSITORY=MakoSP2_Bld_0400

I’ve run a build job and captured the batch file that gets deployed to our build server to actually run the build, the contents of which are:
echo %JENKINS_BUILD_REPOSITORY%
cd "%JENKINS_INT_BUILD_VIEW%\release_eng\Build_scripts\scripts\PS"
powershell.exe -NoProfile -ExecutionPolicy unrestricted -Command "%JENKINS_INT_BUILD_VIEW%\release_eng\Build_scripts\scripts\PS\PSBuild.ps1" ait DB -DownloadProprietaryIfNewer "%JENKINS_BUILD_REPOSITORY%"
exit %ERRORLEVEL%

I’ve executed this batch file on our build server directly and get the expected results:
Using staging area: '\\bosrdfs1\MakoSP2_Build\MakoSP2_Bld_0400'.

The problem is, when the build is run from our Jenkins page, it doesn’t reflect the proper version:
Using staging area: '\\bosrdfs1\MakoSP2_Build\MakoSP2_Bld_0200'.

from system information page
awt.toolkit sun.awt.windows.WToolkit
executable-war D:\Jenkins\jenkins.war
file.encoding Cp1252
file.encoding.pkg sun.io
file.separator \
hudson.diyChunking true
hudson.lifecycle hudson.lifecycle.WindowsServiceLifecycle
java.awt.graphicsenv sun.awt.Win32GraphicsEnvironment
java.awt.headless true
java.awt.printerjob sun.awt.windows.WPrinterJob
java.class.path D:\Jenkins\jenkins.war
java.class.version 51.0
java.endorsed.dirs D:\Jenkins\jre\lib\endorsed
java.ext.dirs D:\Jenkins\jre\lib\ext;C:\Windows\Sun\Java\lib\ext
java.home D:\Jenkins\jre
java.io.tmpdir C:\Windows\TEMP\
java.library.path D:\Jenkins\jre\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:\7-zip;C:\Program Files (x86)\IBM\RationalSDLC\Clearquest\cqcli\bin;C:\Program Files (x86)\IBM\RationalSDLC\common;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Program Files (x86)\IBM\RationalSDLC\ClearCase\bin;c:\Program Files (x86)\Microsoft SQL Server\90\Tools\binn\;C:\Program Files\Microsoft\Web Platform Installer\;C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET Web Pages\v1.0\;C:\Program Files\Microsoft SQL Server\110\Tools\Binn\;C:\Program Files (x86)\Microsoft Team Foundation Server 2012 Power Tools\;C:\Program Files (x86)\Microsoft Team Foundation Server 2012 Power Tools\Best Practices Analyzer\;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\IBM\RationalSDLC\ClearCase\RemoteClient\cteapis;C:\Program Files (x86)\IBM\gsk8\lib;C:\Program Files (x86)\IBM\gsk8\bin;c:\opscode\chef\bin;;.
java.runtime.name Java(TM) SE Runtime Environment
java.runtime.version 1.7.0_25-b17
java.specification.name Java Platform API Specification
java.specification.vendor Oracle Corporation
java.specification.version 1.7
java.vendor Oracle Corporation
java.vendor.url http://java.oracle.com/
java.vendor.url.bug http://bugreport.sun.com/bugreport/
java.version 1.7.0_25
java.vm.info mixed mode
java.vm.name Java HotSpot(TM) Client VM
java.vm.specification.name Java Virtual Machine Specification
java.vm.specification.vendor Oracle Corporation
java.vm.specification.version 1.7
java.vm.vendor Oracle Corporation
java.vm.version 23.25-b01
jline.terminal none
jnidispatch.path C:\Windows\TEMP\jna-1865263461\jna5828704503820800098.dll
line.separator

mail.smtp.sendpartial true
mail.smtps.sendpartial true
os.arch x86
os.name Windows Server 2008 R2
os.version 6.1
path.separator ;
sun.arch.data.model 32
sun.boot.class.path D:\Jenkins\jre\lib\resources.jar;D:\Jenkins\jre\lib\rt.jar;D:\Jenkins\jre\lib\sunrsasign.jar;D:\Jenkins\jre\lib\jsse.jar;D:\Jenkins\jre\lib\jce.jar;D:\Jenkins\jre\lib\charsets.jar;D:\Jenkins\jre\lib\jfr.jar;D:\Jenkins\jre\classes
sun.boot.library.path D:\Jenkins\jre\bin
sun.cpu.endian little
sun.cpu.isalist pentium_pro+mmx pentium_pro pentium+mmx pentium i486 i386 i86
sun.desktop windows
sun.io.unicode.encoding UnicodeLittle
sun.java.command D:\Jenkins\jenkins.war --httpPort=8080
sun.java.launcher SUN_STANDARD
sun.jnu.encoding Cp1252
sun.management.compiler HotSpot Client Compiler
sun.os.patch.level Service Pack 1
svnkit.http.methods Digest,Basic,NTLM,Negotiate
svnkit.ssh2.persistent false
user.country US
user.dir D:\Jenkins
user.home C:\
user.language en
user.name BOSUIP-JENKINS$
user.script
user.timezone America/New_York
user.variant
Plugins

Name ↓

Version

Enabled

Pinned

active-directory 1.39 true false
all-changes 1.3 true false
analysis-core 1.69 true false
ant 1.2 true false
antisamy-markup-formatter 1.2 true true
any-buildstep 0.1 true false
async-http-client 1.7.8 true false
backup-interrupt-plugin 1.0 true false
batch-task 1.17 true false
build-blocker-plugin 1.4.1 true false
build-environment 1.4 true false
build-metrics 1.0 true false
build-monitor-plugin 1.5+build.123 true false
build-name-setter 1.3 true false
build-node-column 0.1 true false
build-pipeline-plugin 1.4.5 true false
build-publisher 1.19 true false
build-timeout 1.14.1 true false
build-user-vars-plugin 1.4 true false
build-view-column 0.2 true false
build-with-parameters 1.3 true false
buildgraph-view 1.1.1 true false
built-on-column 1.1 true false
bulk-builder 1.5 true false
categorized-view 1.8 true false
chef 0.1.3 true false
chef-tracking 1.0 true false
chosen 1.0 true false
claim 2.3 true false
clearcase 1.5.3 true false
cloudbees-folder 4.6.1 true false
conditional-buildstep 1.3.3 true false
configure-job-column-plugin 1.0 true false
console-column-plugin 1.5 true false
console-tail 1.1 true false
copy-data-to-workspace-plugin 1.0 true false
copy-project-link 1.2 true false
copy-to-slave 1.4.3 true false
copyartifact 1.31 true false
coverity 1.5.0 true false
createjobadvanced 1.8 true false
credentials 1.22 true true
custom-job-icon 0.2 true false
cvs 2.12 true true
dashboard-view 2.9.4 true false
deployed-on-column 1.7 true false
deployment-notification 1.2 true false
dynamic-search-view 0.2.1 true false
email-ext 2.38.2 true false
envinject 1.90 true false
external-monitor-job 1.4 true false
extra-columns 1.14 true false
files-found-trigger 1.3 true false
flexible-publish 0.12 true false
global-build-stats 1.3 true false
greenballs 1.14 true false
heavy-job 1.1 true false
hudson-pview-plugin 1.8 true false
iphoneview 0.2 true false
javadoc 1.2 true true
jenkins-multijob-plugin 1.16 true false
job-direct-mail 1.5 true false
job-import-plugin 1.2 true false
job-parameter-summary 0.3 true false
job-restrictions 0.3 true false
jobConfigHistory 2.9 true false
jobgenerator 1.22 true false
jobtemplates 1.0 true false
jobtype-column 1.3 true false
jquery 1.7.2-1 true false
jquery-ui 1.0.2 true false
junit 1.1 true true
junit-realtime-test-reporter 0.2 true false
keyboard-shortcuts-plugin 1.2 true false
ldap 1.6 true false
leastload 1.0.3 true false
locks-and-latches 0.6 true false
logaction-plugin 1.2 true false
logging 0.2.8 true false
mailer 1.11 true true
mapdb-api 1.0.1.0 true false
matrix-auth 1.2 true true
matrix-project 1.4.1 true false
maven-plugin 2.6 true true
msbuild 1.24 true false
multi-slave-config-plugin 1.2.0 true false
nested-view 1.14 true false
next-executions 1.0.9 true false
nodelabelparameter 1.5.1 true false
nodenamecolumn 1.2 true false
pam-auth 1.2 true true
parameterized-trigger 2.25 true false
plain-credentials 1.0 true false
plot 1.7 true false
pollscm 1.2 true false
post-completed-build-result 1.1 true false
postbuild-task 1.8 true false
powershell 1.2 true false
prereq-buildstep 1.1 true false
PrioritySorter 2.9 true false
progress-bar-column-plugin 1.0 true false
project-build-times 1.2.1 true false
project-health-report 1.2 true false
project-stats-plugin 0.4 true false
purge-build-queue-plugin 1.0 true false
qc 1.2.1 true false
rebuild 1.22 true false
recipe 1.2 true false
ruby-runtime 0.12 true false
run-condition 1.0 true false
saferestart 0.3 true false
schedule-build 0.3.3 true false
scm-api 0.2 true false
script-security 1.13 true false
shelve-project-plugin 1.5 true false
simpleclearcase 1.2.2 true false
slack 1.7 true false
slave-setup 1.8 true false
slave-status 1.6 true false
slave-utilization-plugin 1.8 true false
sloccount 1.20 true false
ssh 2.4 true false
ssh-agent 1.5 true false
ssh-credentials 1.10 true true
ssh-slaves 1.9 true true
startup-trigger-plugin 2.4 true false
stepcounter 1.3.2 true false
storable-configs-plugin 1.0 true false
subversion 2.4.3 true true
tasks 4.44 true false
team-views 0.9.0 true false
template-project 1.4.2 true false
template-workflows 1.2 true false
tfs 3.1.1 true false
thinBackup 1.7.4 true false
timestamper 1.5.15 true false
token-macro 1.10 true false
translation 1.12 true true
unreliable-slave-plugin 1.2 true false
upstream-downstream-view 1.005 true false
uptime 1.0 true false
validating-string-parameter 2.3 true false
view-job-filters 1.26 true false
vs-code-metrics 1.7 true false
windows-slaves 1.0 true false