convert: raise Abort instead of NoRepo when CVS pserver auth fails.
At this point we know the source is CVS, so we should not go through
the rest of the converters.
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<title>Mercurial repositories index</title>
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<h2>Mercurial Repositories</h2>
The specified repository "#repo|escape#" is unknown, sorry.
Please go back to the main repository list page.
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