Add a sanity check to repo init invocation.
Add a sanity check to repo init invocation.

This logic is a bit brute force, but it's what it should be; if
repo can't even process the manifest, then we know it's whacked and
repo won't be able to clean up in transitioning manifest.

The cause of this looks to potentially be from a repo regression-
still tracing that out however (frankly I doubt this code has
ever been forced to process a flat out broke manifest anyways).

BUG=chromium-os:32407, chromium-os:37471
TEST=unittests, feeding it a crap manifest.

Change-Id: I90e49176f0a94469af3487c86e905c80f612d82b
Reviewed-on: https://gerrit.chromium.org/gerrit/40260
Tested-by: Brian Harring <fdc2d0a2e2340b623587cee5ea8dff425d1eb1f3@chromium.org>
Reviewed-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>

bpsinc-native/src_third_party_chromite,coreos/chromite,zhang0137/chromite,bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite,zhang0137/chromite,zhang0137/chromite,coreos/chromite,chadversary/chromiumos.chromite,coreos/chromite,bpsinc-native/src_third_party_chromite