mq: upgrade the patch to HG format when adding the author name with qrefresh

When setting the author field with qrefresh (-u|-U), and the patch does have
neither a 'From:' nor a '# User' header, add the author name as such:

- if the patch has a 'Date:' header, add a 'From:' header
- otherwise, upgrade to Mercurial extended patch format and add # From

hgext/mq.py

@@ -145,7 +145,11 b' class patchheader(object):'
                 patchheaderat = self.comments.index('# HG changeset patch')
                 self.comments.insert(patchheaderat + 1, '# User ' + user)
             except ValueError:
-                self.comments = ['From: ' + user, ''] + self.comments
+                if self._hasheader(['Date: ']):
+                    self.comments = ['From: ' + user] + self.comments
+                else:
+                    tmp = ['# HG changeset patch', '# User ' + user, '']
+                    self.comments = tmp + self.comments
         self.user = user
 
     def setdate(self, date):

tests/test-mq-header-date.out

@@ -231,7 +231,8 b' 2: [mq]: 5.patch - test'
 1: Three (again) - test
 0: [mq]: 1.patch - test
 ==== qref -u -d
-From: john
+# HG changeset patch
+# User john
 
 
 diff -r ... 8
@@ -261,7 +262,8 b' 2: [mq]: 5.patch - test'
 1: Three (again) - test
 0: [mq]: 1.patch - test
 ==== qref -u -d
-From: john
+# HG changeset patch
+# User john
 
 Nine
 

tests/test-mq-header-from.out

@@ -32,7 +32,8 b' diff -r ... 2'
 1: [mq]: 2.patch - test
 0: [mq]: 1.patch - mary
 ==== qref -u
-From: jane
+# HG changeset patch
+# User jane
 
 
 diff -r ... 2
@@ -117,7 +118,8 b' 2: Three (again) - maria'
 1: [mq]: 2.patch - jane
 0: [mq]: 1.patch - mary
 ==== qref -u
-From: jane
+# HG changeset patch
+# User jane
 
 Four