[C pkgs (vc)]: [Bug: 21.4.18] can't check in SCCS file with new vc

[Stephen J. Turnbull]

Ville Skyttä writes:

 > Yep, and probably also some time after that - I'm not quite sure what the 
 > policy about how old versions of XEmacs should stuff in the packages tree 
 > support is, but I personally think not only the latest in the 21.4 branch, 
 > but also at least a few minor 21.4.x releases before it.

Agree in principle.  The questions are (a) how frequently will people
run into this problem in the SCCS context, and is it reasonable to ask
them to upgrade just for this, (b) are they going to run into the
problem elsewhere because of other LISP that uses
replace-regexp-in-string, and (c) how much burden is working around
replace-regexp-in-string going to be for developers.  This will
require experience to answer, so your patch stays for the next few
months at least.