hghave: be more tolerant to rst2html output
On Windows, rst2html.bat calls rst2html.py, printing something like:
"rst2html.py (Docutils"
(notice the extra ".py")
% change the id of the tree root
initializing destination source-hg repository
scanning source...
sorting...
converting...
1 Initial add
0 Changed root
% manifest of tip
644 file