patch-2.7 introduced support for git-formatted patches, which are very common in the wild. http://savannah.gnu.org/forum/forum.php?forum_id=7361
Yes, presumably it is better to introduce this feature in a well defined way. As patch-2.7.5 is stable, I don't see any obstacle for adding this to EAPI 7.
The bug has been referenced in the following commit(s): https://gitweb.gentoo.org/proj/pms.git/commit/?id=b0b4f343da9050ec5a10cd0644d7e00b1b36f0c4 commit b0b4f343da9050ec5a10cd0644d7e00b1b36f0c4 Author: Michał Górny <mgorny@gentoo.org> AuthorDate: 2017-09-28 17:50:56 +0000 Commit: Ulrich Müller <ulm@gentoo.org> CommitDate: 2018-03-31 15:30:43 +0000 EAPI 7 requires GNU patch 2.7. Bug: https://bugs.gentoo.org/593786 commands.tex | 13 ++++++++----- eapi-differences.tex | 4 ++++ 2 files changed, 12 insertions(+), 5 deletions(-)}