localrepo: improve readability of _findtags(), readtags() (issue548).
- rename many local variables
- add some comments
- refactor call to line.split() (catch ValueError rather
than checking length of return value: one less local variable)
{header}
<id>{urlbase}{url}</id>
<link rel="self" href="{urlbase}{url}atom-tags"/>
<link rel="alternate" href="{urlbase}{url}tags"/>
<title>{repo|escape}: tags</title>
<summary>{repo|escape} tag history</summary>
<author><name>Mercurial SCM</name></author>
{latestentry%feedupdated}
{entriesnotip%tagentry}
</feed>