Fix two git operation bugs

- gitCommitAll: abort commit when staging (git add -A) fails, e.g.
  due to a stale .git/index.lock.  Previously the failure was ignored
  and commit proceeded on an empty or partial index.

- gitPull: remove explicit branch argument from git pull --rebase.
  Passing both remote and branch can conflict with the branch's
  configured tracking ref, causing 'Cannot rebase onto multiple
  branches'.  Now uses just --rebase <remote>, letting git resolve
  the tracking branch from config.

- Test: index.lock scenario verifies commit is aborted on staging
  failure.

src/Converge.hs

@@ -321,17 +321,20 @@ syncRepo opts logger repo = do
 -- | Stage all changes and commit with an auto-generated message.
 gitCommitAll :: Logger -> FilePath -> IO (ExitCode, Text, Text)
 gitCommitAll logger repoPath = do
-    (_, _, stageErr) <- loggedGit logger repoPath ["add", "-A"]
-    unless (T.null stageErr) $
-        logInfo logger ("git add stderr: " <> stageErr)
-    hostname <- init <$> readProcess "hostname" [] ""
-    loggedGit logger repoPath ["commit", "-m", "converge: auto-commit from " <> hostname]
+    addResult@(addCode, _, addErr) <- loggedGit logger repoPath ["add", "-A"]
+    unless (T.null addErr) $
+        logInfo logger ("git add stderr: " <> addErr)
+    if addCode /= ExitSuccess
+        then pure addResult
+        else do
+            hostname <- init <$> readProcess "hostname" [] ""
+            loggedGit logger repoPath ["commit", "-m", "converge: auto-commit from " <> hostname]
 
--- | Pull from the configured remote and branch.
+-- | Pull from the configured remote, rebasing onto the tracked upstream branch.
 gitPull :: Logger -> RepoConfig -> IO (ExitCode, Text, Text)
 gitPull logger repo =
     loggedGit logger (rcPath repo)
-        ["pull", "--rebase", T.unpack (rcRemote repo), T.unpack (rcBranch repo)]
+        ["pull", "--rebase", T.unpack (rcRemote repo)]
 
 -- | Push to the configured remote and branch.
 gitPush :: Logger -> RepoConfig -> IO (ExitCode, Text, Text)

test/GitCommitSpec.hs

@@ -54,6 +54,19 @@ spec = do
                 countAfter2 <- commitCount repo
                 countAfter2 `shouldBe` countBefore2
 
+        it "aborts commit when staging fails (e.g. index.lock exists)" $ do
+            logger <- testLogger
+            withTempGitRepo $ \repo -> do
+                -- Create a lock file to make git add -A fail
+                writeFile (repo </> ".git" </> "index.lock") "locked"
+                writeFile (repo </> "new.txt") "new file"
+                countBefore <- commitCount repo
+                (code, _, err) <- gitCommitAll logger repo
+                -- Staging fails, so commit should not happen
+                code `shouldSatisfy` (/= ExitSuccess)
+                err `shouldSatisfy` ("index.lock" `T.isInfixOf`)
+                commitCount repo `shouldReturn` countBefore
+
     describe "startup sync" $ do
         it "commits and pushes uncommitted changes on startup" $ do
             logger <- testLogger