Builds on language environment patch from Alice for ticket 2419
As per irc discussion with tomprince, wrapped 'getElementsByTagName' in
try and added code for storing in Step log file. Addresses log.err issue
in pull request comment
Partial Test changes for 2419fix
Modified as per recent comments in pull request and discussion on IRC.
Added test changes for failure conditions for parseGotRevision
Fixes the function definition with the proper check in test revision for
integer value case
Fixes incorrect symbol used in test function, and indentation
Fixes test_corrupt_xml and updated broken test_revision_non_integer
Fixes test_revision_noninteger function
Fixes test_getUnversionedFiles_corrupted_xml test
Merge remote-tracking branch 'origin/2419fix' into 2419fix
Fixes #1808: use different treeStableTimer in AnyBranchScheduler for different sources
Remove suggestion that multi-codebase builds support is elusive.
Merge branch '2419fix' of git://github.com/ShriramK/buildbot
fix small docs errors
add buildrequests filtering by branch and project

Change-Id: I6b865a565a2bfc68be32e86f2e0d2172d768a60c
fix example
SVN: Add option to use 'last chnaged' revision rather than global revision
BuildslaveChoiceParameter and EnforceChosenSlave: force scheduler hooks for explicit slave control
enforceChosenSlave: address review comments
add warning about LoopingCall and TimerService; refs #1038