util: fix %-formatting on docstring by moving a closing parenthesis

We have to do the % formatting over the sysstr, since the things we're
going to splat into it are themselves sysstrs. This is probably
technically wrong-ish, since bt is probably actually a bytestr here,
but this fixes the immediate issue, which was that hg was broken on
Python 3.

mercurial/util.py

@@ -3705,8 +3705,8 b' def bundlecompressiontopics():'
         if not bt or not bt[0]:
             continue
 
-        doc = pycompat.sysstr('``%s``\n    %s' % (
-            bt[0], engine.bundletype.__doc__))
+        doc = pycompat.sysstr('``%s``\n    %s') % (
+            bt[0], engine.bundletype.__doc__)
 
         value = docobject()
         value.__doc__ = doc