Change revlog.heads to walk the revision graph using revision numbers
On the kernel repo:
$ hg heads -q
before after
RevlogNG 1.11 0.52
Revlogv0 0.80 0.69
Since the current code for tags has to find all the heads of the repo,
this also helps there:
$ hg tags
before after
RevlogNG 2.35 1.76
Revlogv0 2.04 1.90
Content-type: text/xml
<rss version="2.0">
<channel>
<link>#url#</link>
<language>en-us</language>