fetch and interactive packages

[brook%biology.nmsu.edu@localhost (Brook Milligan)]

There seems to be an inconsistency in the fetching of distfiles for
packages marked 'interactive fetch' and those that are not.  Normally,
the fetching process will honor a set of alternative distfile
locations through the ${DIST_PATH} variable.  However, for packages
marked 'interactive fetch' the distfile _must_ be located within
${DISTDIR} as per the following line in mk/fetch/fetch.mk:

${DISTDIR}/${_file_}: fetch-check-interactive do-fetch-file error-check

This prevents the possibility of placing the distfiles for
'interactive fetch' packages in an appropriate part of ${DIST_PATH}.
I am noticing this because I have some packages for proprietary
software that requires special downloading.  Of course, those
distfiles should not be intermingled with the redistributable ones in
${DISTDIR}.  Under the current system, it is impossible to have both
'interactive fetch' marked and a special location for this type of
distfile.

I'm not certain what make magic to suggest, but it seems that making
the above line somehow check all the components of ${DIST_PATH} (if
set) would be appropriate.

Thoughts?

Cheers,
Brook