If ANT_HOME is ended by a '\' character, the build fails with a cryptic message:
started
Updating http://svn.apache.org/repos/asf/commons/proper/lang/trunk
At revision 639231
no change for http://svn.apache.org/repos/asf/commons/proper/lang/trunk since
the previous build
[commons-lang] $ cmd.exe /C ant.bat compile && exit %%ERRORLEVEL%%"'
Usage: java [-options] class [args...]
(to execute a class)
or java [-options] -jar jarfile [args...]
(to execute a jar file)

Hudson configuration should prevent the user from entering a problematic path
like this one.

see https://issues.apache.org/bugzilla/show_bug.cgi?id=26947