Merge branch 'ls/p4-tmp-refs'

"git p4" used a location outside $GIT_DIR/refs/ to place its
temporary branches, which has been moved to refs/git-p4-tmp/.

* ls/p4-tmp-refs:
  git-p4: place temporary refs used for branch import under refs/git-p4-tmp

Author: gitster

git-p4.py

@@ -2274,7 +2274,7 @@ def __init__(self):
         self.useClientSpec_from_options = False
         self.clientSpecDirs = None
         self.tempBranches = []
-        self.tempBranchLocation = "git-p4-tmp"
+        self.tempBranchLocation = "refs/git-p4-tmp"
         self.largeFileSystem = None
 
         if gitConfig('git-p4.largeFileSystem'):

t/t9801-git-p4-branch.sh

@@ -300,7 +300,7 @@ test_expect_success 'git p4 clone complex branches' '
 		test_path_is_file file2 &&
 		test_path_is_file file3 &&
 		! grep update file2 &&
-		test_path_is_missing .git/git-p4-tmp
+		test_must_fail git show-ref --verify refs/git-p4-tmp
 	)
 '
 
@@ -352,7 +352,7 @@ test_expect_success 'git p4 sync changes to two branches in the same changelist'
 		test_path_is_file file2 &&
 		test_path_is_file file3 &&
 		! grep update file2 &&
-		test_path_is_missing .git/git-p4-tmp
+		test_must_fail git show-ref --verify refs/git-p4-tmp
 	)
 '