Avoiding conflicts in .hgtags

[Greg Ward]

On 08 December 2008, I said:
> The same thought occurred to me, so I've started writing a very
> simplistic and naive script to merge .hgtags files.  Will share it
> here for feedback when I've got it working.

As threatened, here is my simple, naive hgmergetags script.

Good points:

  * it seems to work
  * I think the code is reasonably clear and easy to follow
  * it preserves order of the base .hgtags
  * similar API to classic Unix diff3 or merge (except it does not
    overwrite any input file: currently it just writes the merge
    result to stdout)

Bad points:

  * it loads everything into memory, so if you have a very large
    .hgtags, you will not like this script
  * does not preserve order of added tags -- they are just tacked on
    to the end (probably only matters if someone manually edits
    .hgtags and inserts a tag)
  * likewise, conflicts are also tacked on at the end
  * no unit tests

I configured it in ~/.hgrc like this:

  [merge-patterns]
  .hgtags = hgmergetags
  
  [merge-tools]
  hgmergetags.args = $local $base $other > $output

Script attached.  Feedback welcome.

       Greg