This likely apply to older versions as well (I don't know if it was truly required at one point), but at least current GIMP simply does not link against libmypaint-gegl.so and only libmypaint-1.3.so, and this dependency only enforce to install a slotted older version of gegl on top of the one used by GIMP. This bug also extend to libmypaint which enabled gegl by default (see old bug #641760) for GIMP when it doesn't need it. I've tested emerging libmypaint without gegl (built while no versions of gegl were on the system) and then emerging a copy of gimp-2.10.6-r1.ebuild without [gegl] on libmypaint and it built without issues and appears to be working normally. Unless I'm missing something like being loaded dynamically for specific uses (which I do not know of), it should be removed. For reference, Debian also doesn't ship libmypaint-gegl.so even with GIMP installed.
I guess you're right. I'll drop it for 2.10.8.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=aa34b0bb76c88fe61df82cf278d2eec99a1550e3 commit aa34b0bb76c88fe61df82cf278d2eec99a1550e3 Author: Sebastian Pipping <sping@gentoo.org> AuthorDate: 2018-11-18 21:03:20 +0000 Commit: Sebastian Pipping <sping@gentoo.org> CommitDate: 2018-11-18 21:06:21 +0000 media-gfx/gimp: 2.10.8 Also sync 9999 and back from dependency media-libs/libmypaint[gegl] down to plain media-libs/libmypaint. Closes: https://bugs.gentoo.org/670990 Closes: https://bugs.gentoo.org/671170 Signed-off-by: Sebastian Pipping <sping@gentoo.org> Package-Manager: Portage-2.3.50, Repoman-2.3.11 media-gfx/gimp/Manifest | 1 + media-gfx/gimp/gimp-2.10.8.ebuild | 222 ++++++++++++++++++++++++++++++++++++++ media-gfx/gimp/gimp-9999.ebuild | 11 +- 3 files changed, 230 insertions(+), 4 deletions(-)