After running poetry shell with oh-my-zsh, I get the following error message when it tries to activate the virtual-env:
*[main][~/coding/ensure_import]$ poetry shell
Spawning shell within /Users/mac10.12/Library/Caches/pypoetry/virtualenvs/ensure-import-3q-JXftD-py3.11
[oh-my-zsh] Would you like to update? [Y/n]
[oh-my-zsh] You can update manually by running `omz update`
*[main][~/coding/ensure_import]$ mulate bash -c '. /Users/mac10.12/Library/Caches/pypoetry/virtualenvs/ensure-import-3q-JXftD-py3.11/bin/activate'
zsh: command not found: mulate
I have never heard of mulate, but it kind of looks like it's supposed to be emulate if you squint a bit?
Running omz update fixed the problem for me -- I think the prompt to update oh-my-zsh was stealing the first character of the emulate command.
I found the answer (and borrowed the command output) from this post here (after running Google translate).
I also made a feature request for no-input update reminders.