git p4: clone --branch should checkout master

When using the --branch argument to "git p4 clone", one
might specify a destination for p4 changes different from
the default refs/remotes/p4/master.  Both cases should
create a master branch and checkout files.

Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-p4.txt

@@ -174,8 +174,7 @@ subsequent 'sync' operations.
 --branch <branch>::
 	Import changes into given branch.  If the branch starts with
 	'refs/', it will be used as is, otherwise the path 'refs/heads/'
-	will be prepended.  The default branch is 'master'.  If used
-	with an initial clone, no HEAD will be checked out.
+	will be prepended.  The default branch is 'p4/master'.
 +
 This example imports a new remote "p4/proj2" into an existing
 git repository:

git-p4.py

@@ -3118,17 +3118,15 @@ def run(self, args):
 
         if not P4Sync.run(self, depotPaths):
             return False
-        if self.branch != "master":
-            if self.importIntoRemotes:
-                masterbranch = "refs/remotes/p4/master"
-            else:
-                masterbranch = "refs/heads/p4/master"
-            if gitBranchExists(masterbranch):
-                system("git branch master %s" % masterbranch)
-                if not self.cloneBare:
-                    system("git checkout -f")
-            else:
-                print "Could not detect main branch. No checkout/master branch created."
+
+        # create a master branch and check out a work tree
+        if gitBranchExists(self.branch):
+            system([ "git", "branch", "master", self.branch ])
+            if not self.cloneBare:
+                system([ "git", "checkout", "-f" ])
+        else:
+            print 'Not checking out any branch, use ' \
+                  '"git checkout -q -b master <branch>"'
 
         # auto-set this variable if invoked with --use-client-spec
         if self.useClientSpec_from_options:

t/t9806-git-p4-options.sh

@@ -27,7 +27,7 @@ test_expect_success 'clone no --git-dir' '
 	test_must_fail git p4 clone --git-dir=xx //depot
 '
 
-test_expect_failure 'clone --branch should checkout master' '
+test_expect_success 'clone --branch should checkout master' '
 	git p4 clone --branch=refs/remotes/p4/sb --dest="$git" //depot &&
 	test_when_finished cleanup_git &&
 	(