[scm-migration-dev] codereview: CR 6738408: can't build using nightly script from gate

[John Zolnowsky x69422/408-404-5064]

I'm seeking codereview for my changes to relieve a minor annoyance.

The webrev is at
        http://cr.opensolaris.org/~johnz/webrev.6738408/

The big insertion and deletion are just the relocation of the otherwise
unmodified which_scm tests to immediately after the determination of
the workspace and parent workspace paths.

                                                Thanks  -JZ