Aligns argument usage of refactored GitcManifest (8c1e9cbef
"manifest_xml: refactor manifest parsing from client management") to fix
the `repo gitc-init` error: `fatal: manifest_file must be abspath`.
Change-Id: I1728032cce3f39ed1077bbb7ef714410c2c49e1a
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/350374
Tested-by: Woody Lin <woodylin@google.com>
Reviewed-by: LaMont Jones <lamontjones@google.com>
Reviewed-by: Xin Li <delphij@google.com>