Bug Fix
This fixes #188 - if you had mixed magefiles in with non-magefiles and then tried to import the magefiles... everything broke. This puts the behavior back to what it was previous to 1.7.0, where we did not set build the magefile itself with the mage build flag.
Changelog
11d1591 dont use -tags=mage when doing mage:imports and compiling (#189)