Please test if it still builds for you without error! That's really important. :D

I haven't tested this, but given there were issues with the equivalent changeset on OpenSFX, I suspect we'll basically need to copy those same changes over. Also the appropriate GitHub Actions infrastructure.

I've looked at the script again, and and OpenSFX, and made the following changes:

• Generate proper bundle name with version number attached (based on Git tag), fix version number in README
• Add findversion.sh
• Fixed unix2dos detection (identical bug in OpenSFX)

As for GitHub Actions, I suggest to do this stuff separately (different PR).

I just pulled the branch and tried to build it, yet it failed.
~/ottd/OpenMSX] kill-hg(+1/-0) 2 ± LC_ALL=C make
Makefile:161: *** unterminated call to function 'shell': missing ')'. Stop.

The problem here is case:
shell is not the same as SHELL

you should use consequently SHELL
(that also fits the style guide that variables are UPPERCASE)

No? Well, kinda, but not quite. $(shell ...) is the function, SHELL is the variable that sets the shell to use. Is /bin/bash not valid on your system, I wonder?
(This also seems very similar to Eddi's OpenTTD/grfcodec#11 )

https://www.gnu.org/software/make/manual/html_node/Shell-Function.html
https://www.gnu.org/software/make/manual/html_node/Choosing-the-Shell.html

Well, it works for me. *shrug*

If in doubt, just copy what already works (OpenSFX). :)

The whole lot should be squashed into a single commit, but that can be done at merge time. I'll have a look at the rest of the changes.

I agree all the commits should be squashed at the end, but not now, before the review/approval is done.