For the record, the bug report on RT, "Fails when mask is /1" is a misunderstanding of the reporter. In fact, the reporter withdrew it; that is, not a bug.
For those suspicious of it, the following can be for reference:
perl -MNet::IP::Match::XS -le'print match_ip("184.108.40.206","127.0.0.0/1")? "yes":"no"'
This should print "no".
What's more, the net-mask /1 is virtually nonsense.
After having dismissed Net-IP-Match for its strange function name, I turned to this module instead. It compiled without a hitch and installed correctly.
It does exactly what the label on the tin says it does, in the way you would expect. I note that there is a nasty bug open on RT (lookups against /1 netblocks don't work), but for my purpose it works well.
The test suite is very skimpy, and could do with a more exhaustive approach (which no doubt would have caught the above bug).