I ran into a problem with an org-src-font-lock-fontify-block and, before I thought to check the parent org-mode repo, I made a fix to the master branch of emacs.
My fix: https://cgit.git.savannah.gnu.org/cgit/emacs.git/commit/?id=c4af4b39018923fdfc22b515acc1f6ba3f2b024d The fix in org-mode: https://cgit.git.savannah.gnu.org/cgit/emacs/org-mode.git/commit/lisp/org-src.el?id=a1a9d408a423d1bf7e07392eef00ce296b3604fb&context=3&ignorews=1&dt=0 These do not strictly conflict, but my change makes the one in org-mode pointless. Any ideas how to resolve this? Mark.