This can be particularly problematic when supporting a mix of SVN, Mercurial and Git repos as the workspace location varies based on the VCS being used, which makes it hard to have common build scripts until an environment has completely transitioned over to one VCS.

Not sure what the last comment refers to, since SVN and Git plugins should also allow project sources to be at top level in the workspace, what I would consider the most obvious mode of operation. (In the case of SVN, you have to specify "." as the checkout directory rather than leaving this field blank, and endure a harmless exception on initial checkout - long ago filed by me.)

SVN allows you to set a "local module directory". This allows you to have a layout like:

$WORKSPACE/checked-out-repo
$WORKSPACE/coverage-reports
$WORKSPACE/test-artifacts
$WORKSPACE/<etc>

With the Git and Mercurial plugins, there's no documented way to replicate that layout. It looks like this was added to the Git plugin yesterday: http://issues.jenkins-ci.org/browse/JENKINS-6357

Right, currently with the Hg plugin you would need to place generated files into a target/ or build/ subdirectory or the like.

Code changed in hudson
User: : jglick
Path:
trunk/hudson/plugins/mercurial/src/main/java/hudson/plugins/mercurial/HgRc.java
http://jenkins-ci.org/commit/33418
Log:
Preparatory to JENKINS-3602, useful to document that the file paths here are of a Hg repository, not necessarily any Hudson workspace.

Code changed in hudson
User: : jglick
Path:
trunk/hudson/plugins/mercurial/src/main/java/hudson/plugins/mercurial/MercurialSCM.java
trunk/hudson/plugins/mercurial/src/main/resources/hudson/plugins/mercurial/MercurialSCM/help-clean.html
http://jenkins-ci.org/commit/33419
Log:
Preparatory to JENKINS-3602, useful to name paths referring to repositories as "repository", not "workspace".

Code changed in hudson
User: : jglick
Path:
trunk/hudson/plugins/mercurial/src/main/java/hudson/plugins/mercurial/MercurialSCM.java
trunk/hudson/plugins/mercurial/src/main/resources/hudson/plugins/mercurial/MercurialSCM/config.jelly
trunk/hudson/plugins/mercurial/src/main/resources/hudson/plugins/mercurial/MercurialSCM/help-subdir.html
trunk/hudson/plugins/mercurial/src/test/java/hudson/plugins/mercurial/ForestTest.java
trunk/hudson/plugins/mercurial/src/test/java/hudson/plugins/mercurial/MercurialSCMTest.java
http://jenkins-ci.org/commit/33423
Log:
[FIXED JENKINS-3602] Permit Hg repo to be cloned into a subdirectory of the workspace.

Code changed in hudson
User: : jglick
Path:
trunk/hudson/plugins/mercurial/src/main/resources/hudson/plugins/mercurial/MercurialSCM/help-subdir.html
http://jenkins-ci.org/commit/33424
Log:
JENKINS-3602 More information.