Merge branch 'jh/maint-do-not-track-non-branches' into maint

* jh/maint-do-not-track-non-branches:
  branch/checkout --track: Ensure that upstream branch is indeed a branch

branch.c

@@ -175,9 +175,14 @@ void create_branch(const char *head,
 			die("Cannot setup tracking information; starting point is not a branch.");
 		break;
 	case 1:
-		/* Unique completion -- good, only if it is a real ref */
-		if (explicit_tracking && !strcmp(real_ref, "HEAD"))
-			die("Cannot setup tracking information; starting point is not a branch.");
+		/* Unique completion -- good, only if it is a real branch */
+		if (prefixcmp(real_ref, "refs/heads/") &&
+		    prefixcmp(real_ref, "refs/remotes/")) {
+			if (explicit_tracking)
+				die("Cannot setup tracking information; starting point is not a branch.");
+			else
+				real_ref = NULL;
+		}
 		break;
 	default:
 		die("Ambiguous object name: '%s'.", start_name);

t/t3200-branch.sh

@@ -223,6 +223,11 @@ test_expect_success \
     'branch from non-branch HEAD w/--track causes failure' \
     'test_must_fail git branch --track my10 HEAD^'
 
+test_expect_success \
+    'branch from tag w/--track causes failure' \
+    'git tag foobar &&
+     test_must_fail git branch --track my11 foobar'
+
 # Keep this test last, as it changes the current branch
 cat >expect <<EOF
 0000000000000000000000000000000000000000 $HEAD $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> 1117150200 +0000	branch: Created from master
@@ -488,6 +493,15 @@ test_expect_success 'autosetuprebase always on an untracked remote branch' '
 	test "z$(git config branch.myr20.rebase)" = z
 '
 
+test_expect_success 'autosetuprebase always on detached HEAD' '
+	git config branch.autosetupmerge always &&
+	test_when_finished git checkout master &&
+	git checkout HEAD^0 &&
+	git branch my11 &&
+	test -z "$(git config branch.my11.remote)" &&
+	test -z "$(git config branch.my11.merge)"
+'
+
 test_expect_success 'detect misconfigured autosetuprebase (bad value)' '
 	git config branch.autosetuprebase garbage &&
 	test_must_fail git branch

t/t6040-tracking-info.sh

@@ -74,20 +74,20 @@ test_expect_success 'status' '
 	grep "have 1 and 1 different" actual
 '
 
-test_expect_success 'status when tracking lightweight tags' '
+test_expect_success 'fail to track lightweight tags' '
 	git checkout master &&
 	git tag light &&
-	git branch --track lighttrack light >actual &&
-	grep "set up to track" actual &&
-	git checkout lighttrack
+	test_must_fail git branch --track lighttrack light >actual &&
+	test_must_fail grep "set up to track" actual &&
+	test_must_fail git checkout lighttrack
 '
 
-test_expect_success 'status when tracking annotated tags' '
+test_expect_success 'fail to track annotated tags' '
 	git checkout master &&
 	git tag -m heavy heavy &&
-	git branch --track heavytrack heavy >actual &&
-	grep "set up to track" actual &&
-	git checkout heavytrack
+	test_must_fail git branch --track heavytrack heavy >actual &&
+	test_must_fail grep "set up to track" actual &&
+	test_must_fail git checkout heavytrack
 '
 
 test_expect_success 'setup tracking with branch --set-upstream on existing branch' '

t/t7201-co.sh

@@ -408,6 +408,15 @@ test_expect_success 'checkout w/--track from non-branch HEAD fails' '
     test "z$(git rev-parse master^0)" = "z$(git rev-parse HEAD)"
 '
 
+test_expect_success 'checkout w/--track from tag fails' '
+    git checkout master^0 &&
+    test_must_fail git symbolic-ref HEAD &&
+    test_must_fail git checkout --track -b track frotz &&
+    test_must_fail git rev-parse --verify track &&
+    test_must_fail git symbolic-ref HEAD &&
+    test "z$(git rev-parse master^0)" = "z$(git rev-parse HEAD)"
+'
+
 test_expect_success 'detach a symbolic link HEAD' '
     git checkout master &&
     git config --bool core.prefersymlinkrefs yes &&
@@ -423,7 +432,6 @@ test_expect_success 'detach a symbolic link HEAD' '
 test_expect_success \
     'checkout with --track fakes a sensible -b <name>' '
     git update-ref refs/remotes/origin/koala/bear renamer &&
-    git update-ref refs/new/koala/bear renamer &&
 
     git checkout --track origin/koala/bear &&
     test "refs/heads/koala/bear" = "$(git symbolic-ref HEAD)" &&
@@ -439,12 +447,6 @@ test_expect_success \
 
     git checkout --track remotes/origin/koala/bear &&
     test "refs/heads/koala/bear" = "$(git symbolic-ref HEAD)" &&
-    test "$(git rev-parse HEAD)" = "$(git rev-parse renamer)" &&
-
-    git checkout master && git branch -D koala/bear &&
-
-    git checkout --track refs/new/koala/bear &&
-    test "refs/heads/koala/bear" = "$(git symbolic-ref HEAD)" &&
     test "$(git rev-parse HEAD)" = "$(git rev-parse renamer)"
 '