trace: restore Progress indicator.

If we are not tracing to stderr, then we should still have progress
indication.

Change-Id: Ifc9678e1fccbd92251e972fcf25aad6369d60e15
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/351195


Reviewed-by: Sam Saccone <samccone@google.com>
Tested-by: LaMont Jones <lamontjones@google.com>
Reviewed-by: Xin Li <delphij@google.com>