Fix inverted logic around [gitc-]init and -c

Instead of not using '-c' for '--current-branch' when using gitc, we
were only using '-c' when using gitc, so we still had the conflict with
the gitc option, and other users still couldn't use '-c'.

Test: repo init -u https://android.googlesource.com/platform/manifest; repo init -c
Test: repo gitc-init -u ... -b ... -c testing
Change-Id: I71e4950a49c281418249f0783c6a2ea34f0d3e2b
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/253795
Reviewed-by: Mike Frysinger <vapier@google.com>
Tested-by: Dan Willemsen <dwillemsen@google.com>
(cherry picked from commit 93293ca47f)

project.py

@@ -2252,6 +2252,9 @@ class Project(object):
       spec.append('tag')
       spec.append(tag_name)
 
+    if self.manifest.IsMirror and not current_branch_only:
+      branch = None
+    else:
       branch = self.revisionExpr
     if (not self.manifest.IsMirror and is_sha1 and depth
         and git_require((1, 8, 3))):

subcmds/init.py

@@ -99,7 +99,7 @@ to update the working directory files.
     cbr_opts = ['--current-branch']
     # The gitc-init subcommand allocates -c itself, but a lot of init users
     # want -c, so try to satisfy both as best we can.
-    if gitc_init:
+    if not gitc_init:
       cbr_opts += ['-c']
     g.add_option(*cbr_opts,
                  dest='current_branch_only', action='store_true',