Use --no-clear-tmp flag to decide whether to remove of old temporary
directories, rather than deciding based on whether script_version is a
commit or a local directory.
Use flock() to prevent sharing crunch-tmp with another job in local dev mode.
Merge branch 'master' into 2316-no-clear-tmp-flag
Merge branch '2316-no-clear-tmp-flag'

closes #2316
refs #2372