3775: Update perlpod. Use items_available. Be more conservative when
using already-cached commit sha1s, expand related comment. Move "skip
if not possible now" checks into subroutines.
3775: Update comment
3775: Update comment
3775: Fix SDK usage.
Merge branch '3775-fetch-git-repo' closes #3775

Conflicts:
	sdk/cli/bin/crunch-job