repopick: Add a way to checkout instead of cherrypick

This helps if you want to take a commit and its dependencies, and not
just a particular commit

Change-Id: Ib245cce560c7b0d6fd03198a8c69a13d4720a4cb
repopick: rmv "else:sys.stderr.write" line

This line executed sys.exit if android_build_top was not detected, causing gerrit cherry-pick to not be executed
Merge "repopick: Add a way to checkout instead of cherrypick" into jb43
Merge remote-tracking branch 'buildPA/jb43' into jb43
Merge remote-tracking branch 'ModdedPA/jb43' into jb43