Use CalculateHistoryDivergence for all remotes

Use CalculateHistoryDivergence to search all remotes. The original
implementation of this method searched all remotes but not
`refs/pull/*`. Keep the original behaviour for the moment.

Author: jcansdale

src/GitHub.Exports/Services/GitService.cs

@@ -132,11 +132,13 @@ public Task<string> GetLatestPushedSha(string path, string remote = "origin")
                             }
                         }
 
-                        // This is a less common case where a branch was forked from a local branch
-                        // which has since had new commits pulled to it.
+                        // This is a less common case where a branch was forked from a branch
+                        // which has since had new commits added to it.
                         var nearestCommonAncestor = repo.Branches
-                            .Where(b => b.IsRemote && b.RemoteName == remote)
-                            .Select(b => repo.ObjectDatabase.CalculateHistoryDivergence(b.Tip, repo.Head.Tip))
+                            .Where(b => b.IsRemote)
+                            .Select(b => b.Tip)
+                            .Distinct()
+                            .Select(c => repo.ObjectDatabase.CalculateHistoryDivergence(c, repo.Head.Tip))
                             .Where(hd => hd.AheadBy != null)
                             .OrderBy(hd => hd.BehindBy)
                             .Select(hd => hd.CommonAncestor)
@@ -145,22 +147,6 @@ public Task<string> GetLatestPushedSha(string path, string remote = "origin")
                         {
                             return nearestCommonAncestor.Sha;
                         }
-
-                        // This is a less case where a branch was forked from a reference rather than a
-                        // branch that is tracking a remote (e.g. from the head of a PR `refs/pull/#/head`).
-                        var branchPrefix = $"refs/remotes/{remote}/";
-                        var pullPrefix = "refs/pull/";
-                        var remoteHeads = repo.Refs.Where(r =>
-                            r.CanonicalName.StartsWith(branchPrefix, StringComparison.Ordinal) ||
-                            r.CanonicalName.StartsWith(pullPrefix, StringComparison.Ordinal))
-                            .ToList();
-                        foreach (var commit in repo.Commits.QueryBy(sortByTopological))
-                        {
-                            if (repo.Refs.ReachableFrom(remoteHeads, new[] { commit }).Any())
-                            {
-                                return commit.Sha;
-                            }
-                        }
                     }
 
                     return null;

test/GitHub.Exports.UnitTests/GitServiceTests.cs

@@ -202,7 +202,7 @@ public async Task TowPossibleRemoteBranches_ReturnNearestCommitSha()
         }
 
         [TestCase("origin", true)]
-        [TestCase("jcansdale", false)]
+        [TestCase("jcansdale", true, Description = "Search all remotes")]
         public async Task BehindRemoteBranch_ReturnRemoteCommitSha(string remoteName, bool expectFound)
         {
             using (var temp = new TempDirectory())
@@ -228,34 +228,6 @@ public async Task BehindRemoteBranch_ReturnRemoteCommitSha(string remoteName, bo
             }
         }
 
-        [TestCase("refs/remotes/origin/master", true)]
-        [TestCase("refs/pull/777/head", true)]
-        [TestCase("refs/heads/other", false)]
-        [TestCase("refs/remotes/other/master", false)]
-        public async Task BehindRefWithCanonicalName_ReturnRemoteCommitSha(string canonicalName, bool expectFound)
-        {
-            using (var temp = new TempDirectory())
-            {
-                string expectSha;
-                var dir = temp.Directory.FullName;
-                using (var repo = new Repository(Repository.Init(dir)))
-                {
-                    AddCommit(repo); // First commit
-                    var commit1 = AddCommit(repo);
-                    var commit2 = AddCommit(repo);
-                    repo.Reset(ResetMode.Hard, commit1);
-                    expectSha = expectFound ? commit1.Sha : null;
-                    repo.Refs.Add(canonicalName, commit2.Id);
-                }
-
-                var target = new GitService(new RepositoryFacade());
-
-                var sha = await target.GetLatestPushedSha(dir).ConfigureAwait(false);
-
-                Assert.That(sha, Is.EqualTo(expectSha));
-            }
-        }
-
         static Commit AddCommit(Repository repo)
         {
             var dir = repo.Info.WorkingDirectory;