Here is a patch with which all tests pass (the Zsh ones, including the new
ones that the patch adds, and my tests mentioned in this thread). The
patch does the following:

- Revert change: 50929: fix handling of ERR_RETURN bent by 50928.
<https://sourceforge.net/p/zsh/code/ci/8839e969bf8f3f129d0efd8ecd51505610a1f01b/>
- Revert change: 50928: fix tests for 50897, mention behavior change in NEWS
<https://sourceforge.net/p/zsh/code/ci/1ba8714a7ac665e661c1b3a716ffe2af73d1e443/>
- Revert change: 50897: nonzero status of complex commands should trigger
ERR_EXIT
<https://sourceforge.net/p/zsh/code/ci/d873ed6026d7b0c48d6e65ec06df491d015a4d59/>
- Add saving and restoring of local_noerrexit in doshfunc in exec.c
- Add "this_noerrexit = 1;" at the very end of exectry in loop.c
- Fix test "ERR_RETURN in "else" branch in nested
function" in C03traps.ztst, to not affect tests coming afterwards
- Add new tests in C03traps.ztst

I'm not sure what to do in Changelog. Should I revert your changes or
instead leave them and comment that the patch reverts them? Also, I have no
clue how you obtain the change numbers (like 50929 and 50928).

Philippe