I built a PLIST for math/bc (a new package) and it made an entry like:
\@unexec ${INSTALL_INFO} --delete --info-dir=%D/info %D/info/bc.info

I removed the front slash.

A "pkg_delete bc" and a "make deinstall" does:

<unset_progname>: unexec command for `--delete
--info-dir=/home/jeremy/netbsd/usr/pkg/info
/home/jeremy/netbsd/usr/pkg/info/bc.info' failed
sh: --: unrecognized option
Usage:  sh [GNU long option] [option] ...
        sh [GNU long option] [option] script-file ...
GNU long options:
        --debug
....
<unset_progname>: unexec command for `--delete
--info-dir=/home/jeremy/netbsd/usr/pkg/info
/home/jeremy/netbsd/usr/pkg/info/dc.info' failed
<unset_progname>: couldn't entirely delete package `bc-1.06'

What happened to the INSTALL_INFO setting?

This pkgsrc is under Linux. This has happened on different packages for
me.

   Jeremy C. Reed
   http://www.reedmedia.net/