convert: add a mode where mercurial_sink skips empty revisions.
The getchanges function of some converter_source classes can return
some false positives. I.e. they sometimes claim that a file "foo"
was changed in some revision, even though its contents are still the
same.
convert_svn is particularly bad, but I think this can also happen with
convert_cvs and, at least in theory, with mercurial_source.
For regular conversions this is not really a problem - as long as
getfile returns the right contents, we'll get a converted revision
with the right contents. But when we use --filemap, this could lead
to superfluous revisions being converted.
Instead of fixing every converter_source, I decided to change
mercurial_sink to work around this problem.
When --filemap is used, we're interested only in revisions that touch
some specific files. If a revision doesn't change any of these files,
then we're not interested in it (at least for revisions with a single
parent; merges are special).
For mercurial_sink, we abuse this property and rollback a commit if
the manifest text hasn't changed. This avoids duplicating the logic
from localrepo.filecommit to detect unchanged files.
#header#
<title>#repo|escape#: tags</title>
<link rel="alternate" type="application/atom+xml"
href="#url#atom-tags" title="Atom feed for #repo|escape#: tags">
<link rel="alternate" type="application/rss+xml"
href="#url#rss-tags" title="RSS feed for #repo|escape#: tags">
</head>
<body>
<div class="buttons">
<a href="#url#log{sessionvars%urlparameter}">changelog</a>
<a href="#url#shortlog{sessionvars%urlparameter}">shortlog</a>
<a href="#url#file/#node|short#/{sessionvars%urlparameter}">manifest</a>
<a type="application/rss+xml" href="#url#rss-tags">rss</a>
<a type="application/atom+xml" href="#url#atom-tags">atom</a>
</div>
<h2>tags:</h2>
<ul id="tagEntries">
#entries%tagentry#
</ul>
#footer#