bug#927: vc-bzr.el with cygwin bzr

[Phillip Lord <phillip.lord@newcastle.ac.uk>]

>>>>> "Stefan" == Stefan Monnier <monnier@iro.umontreal.ca> writes:

  >> My hack is platform specific. A better solution would be, to modify
  >> vc-bzr-command to be either of the form "bzr-program-name" or
  >> '("python name" "bzr name"). vc-bzr-command would need to be
  >> modified to cope. There is couple of other places vc-bzr-command is
  >> used which would need changing also.

  Stefan> A better solution would be to write a w32 wrapper for Bzr (an
  Stefan> plain w32 executable that runs python with the bzr script), so
  Stefan> that it does not rely on cygwin's own handling of #!

I don't think that the two contradict. Both would be possible. But, yes,
a bzr.bat in cygwin would probably solve the problem. 

  Stefan> After all, does Cygwin's bzr work with any other program
  Stefan> that's not part of Cygwin? I'd guess not, which is why I think
  Stefan> the problem is not specific to Emacs.

This depends on how they launch bzr; for vc-bzr, for instance, if vc
used an external shell-command instead of start-process it would work.
Even if emacs was using dos as it's shell, I could reconfigure
bzr-command to be "c:/cygwin/bin/python bzr"; unfortunately, you can't
do this with start-process because the space is interpreted as part of
the command name, and bzr not considered an argument. 

Given that the change I suggested is quite small, is there a problem
with putting it in; I'm willing to send in a patch if you wish. It would
also support the use case where one the user wishes to use a specific
python to run bzr. It should be transparent to other users. 

In the meantime, if I can work out how to do it, I'll write to the
cygwin packager and ask for a bzr.bat to be added to cygwin (having
tested that it works). As you say, it would help to make it more
usuable, irrespective of emacs. 

Phil