feat(blame): Support custom `rev_opts` for blame

The `git blame` CLI offers a repeated `-C` option that can be used to detect
lines that move within/between files. While a slower operation, it yields more
accurate authorship reports.
https://git-scm.com/docs/git-blame#Documentation/git-blame.txt--Cltnumgt

While GitPython does enable passing custom kwargs to the command line `git`
invocation, the fact that kwargs is a dictionary (i.e. no duplicate keys) means
that there was no way to request the `-C` option in `git blame` more than once.

This commit adds an optional `rev_opts` parameter to the `blame` method which
accepts a list of strings to propagate to the CLI invocation of `git blame`. By
using a `List[str]` for `rev_opts`, users of GitPython can pass now the `-C`
option multiple times to get more detailed authorship reports from `git blame`.

1 files changed, 7 insertions, 0 deletions

diff --git a/test/test_repo.py b/test/test_repo.py
index 75b590fe..703dbb43 100644
--- a/test/test_repo.py
+++ b/test/test_repo.py
@@ -553,6 +553,13 @@ class TestRepo(TestBase):
         self.assertEqual(len(res), 1)
         self.assertEqual(len(res[0][1]), 83, "Unexpected amount of parsed blame lines")
 
+    @mock.patch.object(Git, "_call_process")
+    def test_blame_accepts_rev_opts(self, git):
+        res = self.rorepo.blame("HEAD", "README.md", rev_opts=["-M", "-C", "-C"])
+        expected_args = ['blame', 'HEAD', '-M', '-C', '-C', '--', 'README.md']
+        boilerplate_kwargs = {"p" : True, "stdout_as_string": False}
+        git.assert_called_once_with(*expected_args, **boilerplate_kwargs)
+
     @skipIf(
         HIDE_WINDOWS_KNOWN_ERRORS and Git.is_cygwin(),
         """FIXME: File "C:\\projects\\gitpython\\git\\cmd.py", line 671, in execute