gitwrapper: Re-run git init before do full clone

Sometimes full clone failed with error fatal: Not a git repository
and we found that .git/refs/ dir is missing after shallow clone failed.

JIRA: RHELCMP-724
Signed-off-by: Haibo Lin <hlin@redhat.com>

tests/test_scm.py

@@ -192,6 +192,7 @@ class GitSCMTestCase(SCMBaseTest):
                     "git://example.com/git/repo.git",
                     "master",
                 ],
+                ["git", "init"],
                 ["git", "remote", "add", "origin", url],
                 ["git", "remote", "update", "origin"],
                 ["git", "checkout", "master"],