[Ur] Best practices for Mercurial + autogeneration of files?

[Adam Chlipala]

A few people have suggested changing the Ur/Web repository so that 
autogenerated files like 'configure' are not included.  There's a Mantis 
issue here:
     http://www.impredicative.com/mantis/view.php?id=158

Here's my question, which is about an issue not addressed directly in 
the text of that "bug report": What would be the best way to package a 
version control snapshot as a source distribution?  Right now, I use the 
'hg archive' command, which builds a tarball directly from the 
repository.  There is no need to worry about accidentally including 
generated files that should not be distributed.  Would it be necessary 
to get much fancier, with a 'tar' filename blacklist or whitelist, if I 
want to distribute a generated 'configure' file along with other sources 
drawn directly from the repo?