Fix scm tests to not use user configuration

If you configure default branch name in new repos to anything else than
master, there will be failures in tests. The test expects the branch to
be called master, but does not ensure it in any way.

Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

tests/test_scm.py

@@ -317,6 +317,8 @@ class GitSCMTestCaseReal(SCMBaseTest):
                 "git",
                 "--git-dir=%s" % git_dir,
                 "--work-tree=%s" % self.gitRepositoryLocation,
+                "-c",
+                "init.defaultBranch=master",
                 "init",
             ],
             workdir=self.gitRepositoryLocation,