Thanks to Andy, Hrvoje and Tor for their explanations.
Jareth, this intensifies my desire to upgrade CVS. I'm willing to
install and test the transition. I could start running CVS 1.10.7
personally, but the risk of unwanted interaction between CVS 1.9 and
1.10 seems too high. You can't even find cvs-1.9 at
cyclic.com anymore.
I will hack a script that applies patches from mail buffers. But I'm
wedded to perl for this sort of thing. I refuse to use sed.
Martin