eups tries to declare packages in the wrong place

[r-owen]

eups insists on creating ~/.eups/ups_db when the startup script is run and then sometimes on using it, even when it is not wanted. I finally made it unwritable so I could track down when it was being used.

I have found one reproducible instance (on El Capitan using Python 2.7): when I try to declare and tag a package at the same time:

localhost$ eups declare -r . skymap git -t rowen
eups declare: [Errno 13] Permission denied: '/Users/rowen/.eups/ups_db/skymap'

If I declare the package without tagging first, then all works as desired, including being able to then tag it (using the ugly syntax shown or the cleaner eups declare skymap git -t rowen):

localhost$ eups declare -r . skymap git
localhost$ eups list -v skymap
   2015_10.0-4-g65a3ccf /Users/rowen/UW/LSST/lsstsw/stack /Users/rowen/UW/LSST/lsstsw/stack/DarwinX86/skymap/2015_10.0-4-g65a3ccf   current b1841
   git        /Users/rowen/UW/LSST/lsstsw/stack /Users/rowen/UW/LSST/lsstsw/build/skymap               
localhost$ eups declare -r . skymap git -t rowen
localhost$ eups list -v skymap
   2015_10.0-4-g65a3ccf /Users/rowen/UW/LSST/lsstsw/stack /Users/rowen/UW/LSST/lsstsw/stack/DarwinX86/skymap/2015_10.0-4-g65a3ccf   current b1841
   git        /Users/rowen/UW/LSST/lsstsw/stack /Users/rowen/UW/LSST/lsstsw/build/skymap                user:rowen

This is a problem for people who are trying to use eups to manage more than one stack, since the products from one stack will leak into another. I assume there is some important use case for ~/.eups/ups_db but if not, it would be nice to lose it once and for all. If so, it would be nice to be able to disable it in a way that is more direct than making it unwritable.