As discussed in IRC, a note to the effect that patch files not starting with "patch-" will be ignored would alleviate frustration in people who just want to port a few things they need and go on with their main task of using them.
As the frustrated person in question, I very much +1 this issue.
Also, it would be nice to add a link to https://www.freebsd.org/doc/en_US.ISO8859-1/books/porters-handbook/book.html to the landing page of the porters' handbook, as it is *very* handy for looking things up (just ctrl+f over the whole book).
Before PauAmma directed me to it, I didn't even know it existed. Could've saved me a few hours of confused clicking and skimming through the handbook, trying to find where THAT ONE THING I NEED RIGHT NOW™ was documented. :P
(In reply to phryk from comment #1)
Re the latter, see https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=244538 .
While here, we should add that EXTRA_PATCHES should not start with patch-*
Otherwise it will be unconditionally applied (the name starts with patch-). Then in the Makefile if the condition for the EXTRA_PATCHES is met, it will be tried again, failing in doing so.