Add envar to replace shallow clones with partial

An investigation go/git-repo-shallow shows a number of problems
when doing a shallow git fetch/clone. This change introduces an
environment variable REPO_ALLOW_SHALLOW. When this environment variable
is set to 1 during a repo init or repo sync all shallow git fetch
commands are replaced with partial fetch commands. Any shallow
repository needing update is unshallowed. This behavior continues until
a subsequent repo sync command is run with REPO_ALLOW_SHALLOW set to 1.

Bug: b/274340522
Change-Id: I1c3188270629359e52449788897d9d4988ebf280
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/374754
Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Tested-by: Jason Chang <jasonnc@google.com>

0 files changed, 0 insertions, 0 deletions