Bug: syntax highlighting in ox-odt and emacs26+ broken [9.1.2 (9.1.2-elpa @ /home/jay/Code/tmp/emacs/lisp/org/)]

[Jay Kamat <jaygkamat@gmail.com>]

Hi Everyone,

I think 'francisv' from the #org-mode irc channel found a interesting
bug in emacs or org mode. I don't know enough about emacs to figure out
exactly what's going on, so I'll provide as much information as I'm able
to find out.

orgmode syntax highlighting when exporting to ox-odt in emacs 26 seems
to be broken. This is not reproducible under emacs 25 at all. In
addition, this seems to be dependent on which emacs is compiling org
bytecode.

Steps to Reproduce:
1. Compile Emacs *26* from source
2. Load an org file with the following (built-in org):

#+BEGIN_SRC c
int main() {
    return 0;
}
#+END_SRC

3. Export to odt via C-c C-e o o 
4. Open file in libreoffice

Expected Results

Syntax highlighting for the code block as in emacs25

Actual Results

Code seems to be colored in a single color, interestingly, this is *not*
black.

(I can provide screenshots if that would be helpful)

After poking around, I found a bit more information on how to reproduce
it:

Environments with working syntax export:
1. Emacs25, always (unless unrelated errors are present)
2. Emacs26, when running org compiled with emacs 25 (from elpa/repo)
3. Emacs26, when running org 'interpreted' (not compiled to bytecode)

Environments with broken syntax export:
1. Emacs26 when compiled from source, using builtin org
2. Emacs26 when org is compiled with Emacs 26 (from elpa/repo)

I tested all emacs versions on org 0b83168465, changing which version
org was compiled with by modifying the EMACS variable in local.mk in
org. I also ran everything in ~emacs -Q~.

I attempted to bisect emacs to find which change in emacs is causing
this, bug I wasn't able to compile some older versions of emacs. I was
able to find that it was '14 revisions away from 5f3379b338' but I don't
know if that's helpful.

A stackexchange question about this is here:
https://emacs.stackexchange.com/questions/36023/how-to-export-babel-source-blocks-with-syntax-highlighting-to-odt-in-org-mode-in

This is probably not a bug in org mode (but rather in emacs 26) but I
wanted to post it here first to see if anyone had any idea what could be
causing this. If this dosen't seem like an org bug, I'm happy to
redirect it to emacs bug reports.

Please let me know if anyone has any questions, and apologies if
anything is wrong about this report.

Emacs  : GNU Emacs 26.0.60 (build 5, x86_64-pc-linux-gnu, GTK+ Version 3.22.11)
 of 2017-10-07
Package: Org mode version 9.1.2 (9.1.2-elpa @ /home/jay/Code/tmp/emacs/lisp/org/)

Thanks,
-Jay