ensure each message line printed in the Mercurial hook gets a trailing newline

I noticed that the exception printed in the previous commit started on the same
line as the print for the `str(e)` case right before it.  Since this also prints
the content of urllib2.URLError.read(), it seems better to remove any existing
newline and re-add it, than to just assume the `str(e)` case was the only
problem.

scm-plugins/scm-hg-plugin/src/main/resources/sonia/scm/python/scmhooks.py

@@ -46,7 +46,7 @@ def printMessages(ui, msgs):
   for line in msgs:
     if line.startswith("_e") or line.startswith("_n"):
       line = line[2:];
-    ui.warn(line);
+    ui.warn('%s\n' % line.rstrip())
 
 def callHookUrl(ui, repo, hooktype, node):
   abort = True