At title says, Pandoc is used during compile-time of mkvtoolnix. I get a compile failure every time both (and dependencies of the latter) are involved in a 'world' update. I haven't tested behaviour of mkvtoolnix build behaviour if pandoc is not installed at all.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=144eb6b46b41f5dec53c855f2b0b15ed68c1da63 commit 144eb6b46b41f5dec53c855f2b0b15ed68c1da63 Author: Alexis Ballier <aballier@gentoo.org> AuthorDate: 2020-09-30 17:08:11 +0000 Commit: Alexis Ballier <aballier@gentoo.org> CommitDate: 2020-09-30 17:08:24 +0000 media-video/mkvtoolnix: bump to 50.0.0. Fix automagic on pandoc Closes: https://bugs.gentoo.org/692018 Package-Manager: Portage-3.0.8, Repoman-3.0.1 Signed-off-by: Alexis Ballier <aballier@gentoo.org> media-video/mkvtoolnix/Manifest | 1 + media-video/mkvtoolnix/mkvtoolnix-50.0.0.ebuild | 130 ++++++++++++++++++++++++ media-video/mkvtoolnix/mkvtoolnix-9999.ebuild | 4 + 3 files changed, 135 insertions(+)