Confirmed.  I'm not sure what's going wrong here: as I understand it,
this function depends on the Term::ReadKey Perl module, provided by the
Cygwin perl-TermReadKey package, but that package is correctly listed as
both a buildtime and runtime dependency for the git package.

I'll add to my queue to do some more debugging, but I'm not expecting to
have time to do any serious investigation here for a while.  Obviously
if anyone else is able to identify the problem, I'm very happy to
consider patches!

Adam
(Cygwin Git maintainer)   Thanks for looking on this