bitbake: fetch/git: Fix local clone url to make it work with repo

The "git clone /path/to/git/objects_symlink" couldn't work after the following
change:

https://github.com/git/git/commit/6f054f9fb3a501c35b55c65e547a244f14c38d56

But repo command manages the git repo as symlinks, so check whether the objects
is an symlink to fix the problem:

* Nothing is changed if git/objects is not a symlink
* Use "git clone file://" when git/objects is a symlink

(Bitbake rev: 5b105e76dd7de3b9a25b17b397f2c12c80048894)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit a0d8108eba8d542707740d00c66c1c5f5b963f18)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

bitbake/lib/bb/fetch2/git.py

@@ -367,9 +367,13 @@ class Git(FetchMethod):
 
         # If the repo still doesn't exist, fallback to cloning it
         if not os.path.exists(ud.clonedir):
-            # We do this since git will use a "-l" option automatically for local urls where possible
+            # We do this since git will use a "-l" option automatically for local urls where possible,
+            # but it doesn't work when git/objects is a symlink, only works when it is a directory.
             if repourl.startswith("file://"):
-                repourl = repourl[7:]
+                repourl_path = repourl[7:]
+                objects = os.path.join(repourl_path, 'objects')
+                if os.path.isdir(objects) and not os.path.islink(objects):
+                    repourl = repourl_path
             clone_cmd = "LANG=C %s clone --bare --mirror %s %s --progress" % (ud.basecmd, shlex.quote(repourl), ud.clonedir)
             if ud.proto.lower() != 'file':
                 bb.fetch2.check_network_access(d, clone_cmd, ud.url)