The `format' section of the auto.master(5) man page says: Second field is the map file to be consulted for this mount-point. This field is of the form maptype:mapname, where maptype is one of the supported map types (file, program, yp, nisplus, hesiod), and mapname is the name of the map. However, the script /etc/rc.d/init.d/autofs does not appear to accept this input format. In particular, it interprets a field of "program:auto.home" to mean a map file named /etc/program:auto.home, rather than treating it as a program. It detects program map files by checking the executable bit. Either behavior makes sense, but the docs should be consistent with the code.
This should already be resolved in Raw Hide, or in today's beta release, where the autofs init script has been heavily modified to match both the documented and expected behavior. Please reopen this bug ID if you find that this is not the case.