Figured out how to reproduce vfork/rsync bug!

[Jonathan Kamens <jik at curl dot com>]

I found some time yesterday (where "found some time" is defined as
"stayed up until 1:30am") working on tracking this down further.  I've
discovered that it appears to be related to a very long environment
variable.  In particular, if you put this script into a file and run
it:

  #!/bin/sh

  export 'INCLUDE=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'
  rsync /tmp/foo/ /tmp/bar/

You'll get the Cygwin failure I've previously reported, but if you
delete one 'x' from the end of the variable setting in the script, the
failure goes away.

I'm going to keep plugging away at trying to track this down now that
I have a specific cause in sight, but if anyone has any insights to
offer as to what could be causing it or where I should be looking, I'm
all ears.

  jik