notify: fix diffstat printing

notify.diff() keeps line breaks in the diff buffer before calling
patch.diffstat().
patch.diffstat() however adds another line break when feeding diffstat input.
The added extra empty line leads to erroneous diffstat output.
This fix removes the line breaks in notify.diff() and adds it back to print them.

hgext/notify.py

@@ -233,9 +233,11 b' class notifier(object):'
     def diff(self, node, ref):
         maxdiff = int(self.ui.config('notify', 'maxdiff', 300))
         prev = self.repo.changelog.parents(node)[0]
+
         self.ui.pushbuffer()
         patch.diff(self.repo, prev, ref, opts=patch.diffopts(self.ui))
-        difflines = self.ui.popbuffer().splitlines(1)
+        difflines = self.ui.popbuffer().splitlines()
+
         if self.ui.configbool('notify', 'diffstat', True):
             s = patch.diffstat(difflines)
             # s may be nil, don't include the header if it is
@@ -249,7 +251,7 b' class notifier(object):'
             difflines = difflines[:maxdiff]
         elif difflines:
             self.ui.write(_('\ndiffs (%d lines):\n\n') % len(difflines))
-        self.ui.write(*difflines)
+        self.ui.write("\n".join(difflines))
 
 def hook(ui, repo, hooktype, node=None, source=None, **kwargs):
     '''send email notifications to interested subscribers.