special patch for /CVS/entries permissions

[valexa]

I am in the position of needing that the /CVS/entries file that is
created on checkout to be group writable

By default it is only owner writable and even if i manually chmod it,
on the next checkout the generic permissions are restored.

I aim to change those generic permissions from 644 to 664

I am in the process of finding where exactly in the source code of cvs
are these permissions defined , and i wonder if anyone has any ideea
about this