If the value obtained is None we now set the variable to
'' instead, in an attempt to make execve() happier about
our 3rd argument, the env dictionary.
Signed-off-by: Shawn O. Pearce <sop@google.com>
REPO_PATH is the path relative the the root of the client.
REPO_REMOTE is the name of the remote system from the manifest.
REPO_LREV is the name of the revision from the manifest, but
translated to something the local repository knows.
REPO_RREV is the name of the revision from the manifest.
This allows us to do commands like:
repo forall -c 'echo "(cd $REPO_PATH && git checkout `git rev-parse HEAD`)"'
