PLEASE! STOP THAT NONESENSE! inkscape CANNOT be a dependency for imagemagick, because: 1. It creates circular dependency without ANY reason. 2. Its is NOT required to build imagemagick nor to run it. 3. It is VERY BAD design. If you insist that some 0.01% of users may need it, please consider adding INKSCAPE USE flag. P.S. Honestly I was shocked seeing that in new ebuild. Stop it.
Your issue is real, but seems to be already reported in bug 684686. *** This bug has been marked as a duplicate of bug 684686 ***