repo forall .. variable name

repo forall 可以用的 變數，在 subcmds/forall.py 中有說明

# Environment

pwd is the project's working directory.  If the current client is
a mirror client, then pwd is the Git repository.

REPO_PROJECT is set to the unique name of the project.

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, translated
to a local tracking branch.  If you need to pass the manifest
revision to a locally executed git command, use REPO_LREV.

REPO_RREV is the name of the revision from the manifest, exactly
as written in the manifest.

REPO_COUNT is the total number of projects being iterated.

REPO_I is the current (1-based) iteration count. Can be used in
conjunction with REPO_COUNT to add a simple progress indicator to your
command.

REPO__* are any extra environment variables, specified by the
"annotation" element under any project element.  This can be useful
for differentiating trees based on user-specific criteria, or simply
annotating tree details.