[PATCHv1 2/2] git-p4: work with a detached head

[Luke Diamand <luke@diamand.org>]

When submitting, git-p4 finds the current branch in
order to know if it is allowed to submit (configuration
"git-p4.allowSubmit").

On a detached head, detecting the branch would fail, and
git-p4 would report a cryptic error.

This change teaches git-p4 to recognise a detached head and
submit successfully.

Signed-off-by: Luke Diamand <luke@diamand.org>
---
 git-p4.py               | 18 ++++++++++++------
 t/t9800-git-p4-basic.sh |  2 +-
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/git-p4.py b/git-p4.py
index 2677c89..a22ae01 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -1651,8 +1651,8 @@ class P4Submit(Command, P4UserMap):
     def run(self, args):
         if len(args) == 0:
             self.master = currentGitBranch()
-            if len(self.master) == 0 or not gitBranchExists("refs/heads/%s" % self.master):
-                die("Detecting current git branch failed!")
+            if self.master == "undefined":
+                self.master = None
         elif len(args) == 1:
             self.master = args[0]
             if not branchExists(self.master):
@@ -1660,9 +1660,10 @@ class P4Submit(Command, P4UserMap):
         else:
             return False
 
-        allowSubmit = gitConfig("git-p4.allowSubmit")
-        if len(allowSubmit) > 0 and not self.master in allowSubmit.split(","):
-            die("%s is not in git-p4.allowSubmit" % self.master)
+        if self.master:
+            allowSubmit = gitConfig("git-p4.allowSubmit")
+            if len(allowSubmit) > 0 and not self.master in allowSubmit.split(","):
+                die("%s is not in git-p4.allowSubmit" % self.master)
 
         [upstream, settings] = findUpstreamBranchPoint()
         self.depotPath = settings['depot-paths'][0]
@@ -1730,7 +1731,12 @@ class P4Submit(Command, P4UserMap):
         self.check()
 
         commits = []
-        for line in read_pipe_lines(["git", "rev-list", "--no-merges", "%s..%s" % (self.origin, self.master)]):
+        if self.master:
+            commitish = self.master
+        else:
+            commitish = 'HEAD'
+
+        for line in read_pipe_lines(["git", "rev-list", "--no-merges", "%s..%s" % (self.origin, commitish)]):
             commits.append(line.strip())
         commits.reverse()
 
diff --git a/t/t9800-git-p4-basic.sh b/t/t9800-git-p4-basic.sh
index 114b19f..0730f18 100755
--- a/t/t9800-git-p4-basic.sh
+++ b/t/t9800-git-p4-basic.sh
@@ -241,7 +241,7 @@ test_expect_success 'unresolvable host in P4PORT should display error' '
 	)
 '
 
-test_expect_failure 'submit from detached head' '
+test_expect_success 'submit from detached head' '
 	test_when_finished cleanup_git &&
 	git p4 clone --dest="$git" //depot &&
 	(
-- 
2.6.0.rc0.133.ga438a11.dirty