git checkout master --
'
+test_expect_success 'checkout notices failure to lock HEAD' '
+ test_when_finished "rm -f .git/HEAD.lock" &&
+ >.git/HEAD.lock &&
+ test_must_fail git checkout -b other
+'
+
+test_expect_success 'create ref directory/file conflict scenario' '
+ git update-ref refs/heads/outer/inner master &&
+
+ # do not rely on symbolic-ref to get a known state,
+ # as it may use the same code we are testing
+ reset_to_df () {
+ echo "ref: refs/heads/outer" >.git/HEAD
+ }
+'
+
+test_expect_success 'checkout away from d/f HEAD (unpacked, to branch)' '
+ reset_to_df &&
+ git checkout master
+'
+
+test_expect_success 'checkout away from d/f HEAD (unpacked, to detached)' '
+ reset_to_df &&
+ git checkout --detach master
+'
+
+test_expect_success 'pack refs' '
+ git pack-refs --all --prune
+'
+
+test_expect_success 'checkout away from d/f HEAD (packed, to branch)' '
+ reset_to_df &&
+ git checkout master
+'
+
+test_expect_success 'checkout away from d/f HEAD (packed, to detached)' '
+ reset_to_df &&
+ git checkout --detach master
+'
test_done