mq: autodetect an existing git patch during qrefresh (issue 491)

hgext/mq.py

@@ -909,7 +909,16 b' class queue:'
         patchparent = self.qparents(repo, top)
         message, comments, user, date, patchfound = self.readheaders(patchfn)
 
-        patchf = self.opener(patchfn, "w")
+        patchf = self.opener(patchfn, 'r+')
+
+        # if the patch was a git patch, refresh it as a git patch
+        for line in patchf:
+            if line.startswith('diff --git'):
+                self.diffopts().git = True
+                break
+        patchf.seek(0)
+        patchf.truncate()
+
         msg = opts.get('msg', '').rstrip()
         if msg:
             if comments:

tests/test-mq

@@ -319,6 +319,8 b" hg log -vC --template '{rev} {file_copie"
 hg qrefresh --git
 cat .hg/patches/bar
 hg log -vC --template '{rev} {file_copies%filecopy}\n' -r .
+hg qrefresh
+grep 'diff --git' .hg/patches/bar
 
 echo
 hg up -C 1

tests/test-mq.out

@@ -325,6 +325,8 b' diff --git a/foo b/baz'
 rename from foo
 rename to baz
 2 baz (foo)
+diff --git a/bar b/bar
+diff --git a/foo b/baz
 
 1 files updated, 0 files merged, 2 files removed, 0 files unresolved
 2 files updated, 0 files merged, 1 files removed, 0 files unresolved