prefix later, but doing so with @cwd %%OLDPREFIX%% (having
PLIST_SUB+="OLDPREFIX=${PREFIX}") hardcodes the value in the packing
list. That's not really a problem when dealing with ports but that's
a problem with packages since pkg_add -p option only overrides the
first @cwd occurrence.
This patch allow us to use @cwd without any argument. If no
directory argument is given, it will set current working directory
to the first prefix given by the @cwd command.
PR: bin/77212
Submitted by: flz
ce036f4091