fix(git ops): moved git operations into vcsserver and use libgit2 when possible.

This fixes issues with calling merge-base on repos that are not fully in sync

vcsserver/remote/git_remote.py

@@ -149,6 +149,7 b' def get_obfuscated_url(url_obj):'
 
 
 class GitRemote(RemoteBase):
+    COMMIT_ID_PAT = re.compile(rb'[0-9a-fA-F]{40}')
 
     def __init__(self, factory):
         self._factory = factory
@@ -633,6 +634,14 b' class GitRemote(RemoteBase):'
             return new_commit_id
 
     @reraise_safe_exceptions
+    def compare_commits(self, wire, commit_id1, commit_id2):
+        output, __ = self.run_git_command(
+            wire, ['log', '--reverse', '--pretty=format: %H', '-s',
+             f'{commit_id1}..{commit_id2}'])
+        commits = [safe_str(commit_id) for commit_id in self.COMMIT_ID_PAT.findall(output)]
+        return commits
+
+    @reraise_safe_exceptions
     def commit(self, wire, commit_data, branch, commit_tree, updated, removed):
 
         def mode2pygit(mode):
@@ -872,6 +881,14 b' class GitRemote(RemoteBase):'
         return revs
 
     @reraise_safe_exceptions
+    def get_common_ancestor(self, wire, rev1, rev2):
+        repo_init = self._factory.repo_libgit2(wire)
+        with repo_init as repo:
+            ancestor_id = repo.merge_base(rev1, rev2)
+
+        return str(ancestor_id)
+
+    @reraise_safe_exceptions
     def get_object(self, wire, sha, maybe_unreachable=False):
         cache_on, context_uid, repo_id = self._cache_on(wire)
         region = self._region(wire)