mq: allow lines starting with '--- ' in patch messages

hgext/mq.py

@@ -96,13 +96,11 b' class patchheader(object):'
 
         for line in file(pf):
             line = line.rstrip()
-            if line.startswith('diff --git'):
+            if (line.startswith('diff --git')
+                or (diffstart and line.startswith('+++ '))):
                 diffstart = 2
                 break
-            if diffstart:
-                if line.startswith('+++ '):
-                    diffstart = 2
-                break
+            diffstart = 0 # reset
             if line.startswith("--- "):
                 diffstart = 1
                 continue

tests/test-mq-qimport

@@ -43,6 +43,7 b' Text before patch.'
 First line of commit message.
 
 More text in commit message.
+--- confuse the diff detection
 
 diff --git a/x b/x
 new file mode 100644