[BUG] unknown-left unknown-right on diff of identical revisions

[Jerry Nairn]

Hi,
When you do a human readable colored or long colored diff of revisions 
which happen to be identical, like you might get by merging two branches, 
the revisions shown in the page are 'unknown-left' and 'unknown-right'. 
Maybe this is because of a difference in the way rcsdiff works on 
different platforms. I don't know.
In the human_readable_diff subroutine, rcsdiff output is parsed to get 
revision numbers. (Seems kind of goofy when you already have the revision 
numbers.) When there is no output from rcsdiff, this doesn't work, and 
these lines set the revisions to 'unknown-left' and 'unknown-right':

  $rev1  = 'unknown-left'  unless defined($rev1);
  $rev2  = 'unknown-right' unless defined($rev2);

I added these lines before those two lines above to fix this problem. I'm 
sure there's a nicer way to do this.

  $rev1  = $input{tr1} unless defined($rev1);
  $rev2  = $input{tr2} unless defined($rev2);

Sorry if you get this twice. I sent this yesterday, but got no bounced 
mail and did not see it on the list.
Cheers,

Jerry Nairn