how to install git-annex ver=7 on a Mac?

[mrneont]

@leej3

I have a Mac OS 10.15. I am trying to run the testing framework, and get all the way to the 2nd data-lad publish, as described in this issue:
#2

I am not sure what that error means, but this part of the instructions:
https://github.com/afni/afni_ci_test_data#git-configuration
says that git-annex should "likely be" ver=7, but installing datalad always brings a dependency of git-annex ver=8. I don't even know how to install git-annex ver=7 on this Mac OS.

Things I have tried:

A) The building the conda env with the distributed environment.yml: only specifies datalad, and I only get git-annex ver=8.

B) brew install git-annex : only installs ver=8. Trying brew install git-annex@7 to try to specify a version only produces an error (even if I try the full version number with the dot).

C) Trying to follow the instructions here (which you suggested in an email):
https://itnext.io/how-to-install-an-older-brew-package-add141e58d32
I followed its instructions for git-annex, leading me to run this, but git-annex is not allowed to install in this way, as the text output implies:

$ brew install https://raw.githubusercontent.com/Homebrew/homebrew-core/58523dde0519e92b494a833c66baea59389d4e84/Formula/git-annex.rb
Updating Homebrew...
==> Auto-updated Homebrew!
Updated 2 taps (homebrew/core and homebrew/cask).
==> Updated Formulae
Updated 6 formulae.
==> Updated Casks
Updated 1 cask.

Traceback (most recent call last):
9: from /usr/local/Homebrew/Library/Homebrew/brew.rb:122:in `<main>'
8: from /usr/local/Homebrew/Library/Homebrew/cmd/install.rb:131:in `install'
7: from /usr/local/Homebrew/Library/Homebrew/cli/parser.rb:303:in `parse'
6: from /usr/local/Homebrew/Library/Homebrew/cli/parser.rb:634:in `formulae'
5: from /usr/local/Homebrew/Library/Homebrew/cli/parser.rb:634:in `map'
4: from /usr/local/Homebrew/Library/Homebrew/cli/parser.rb:638:in `block in formulae'
3: from /usr/local/Homebrew/Library/Homebrew/formulary.rb:404:in `factory'
2: from /usr/local/Homebrew/Library/Homebrew/formulary.rb:180:in `get_formula'
1: from /usr/local/Homebrew/Library/Homebrew/formulary.rb:185:in `klass'
/usr/local/Homebrew/Library/Homebrew/formulary.rb:277:in `load_file': Invalid usage: Installation of git-annex from a GitHub commit URL is unsupported! `brew extract git-annex` to a stable tap on GitHub instead. (UsageError)
12: from /usr/local/Homebrew/Library/Homebrew/brew.rb:155:in `<main>'
11: from /usr/local/Homebrew/Library/Homebrew/brew.rb:157:in `rescue in <main>'
10: from /usr/local/Homebrew/Library/Homebrew/help.rb:64:in `help'
9: from /usr/local/Homebrew/Library/Homebrew/help.rb:83:in `command_help'
8: from /usr/local/Homebrew/Library/Homebrew/help.rb:103:in `parser_help'
7: from /usr/local/Homebrew/Library/Homebrew/cli/parser.rb:303:in `parse'
6: from /usr/local/Homebrew/Library/Homebrew/cli/parser.rb:634:in `formulae'
5: from /usr/local/Homebrew/Library/Homebrew/cli/parser.rb:634:in `map'
4: from /usr/local/Homebrew/Library/Homebrew/cli/parser.rb:638:in `block in formulae'
3: from /usr/local/Homebrew/Library/Homebrew/formulary.rb:404:in `factory'
2: from /usr/local/Homebrew/Library/Homebrew/formulary.rb:180:in `get_formula'
1: from /usr/local/Homebrew/Library/Homebrew/formulary.rb:185:in `klass'
/usr/local/Homebrew/Library/Homebrew/formulary.rb:277:in `load_file': Invalid usage: Installation of git-annex from a GitHub commit URL is unsupported! `brew extract git-annex` to a stable tap on GitHub instead. (UsageError)

D) ... So I went the "brew extract ..." route, suggested by the above. First I googled about it: there were no hits for "brew extract git-annex", but for just "brew extract", there was this helpful/general page:
https://cmichel.io/how-to-install-an-old-package-version-with-brew/
(I also did try again "brew install git-annex@7.20200219", thinking the more specific version might get found, but that failed.)
I did these steps then:

$ brew tap-new $USER/local-git-annex
$ brew extract --version=7 git-annex $USER/local-git-annex
==> Searching repository history
Warning: Calling `cellar` in a bottle block is deprecated! Use `brew style --fix` on the formula to update the style or use `sha256` with a `cellar:` argument instead.
Please report this issue to the homebrew/core tap (not Homebrew/brew or Homebrew/core), or even better, submit a PR to fix it:
  /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/git-annex.rb:15

[... and MANY MORE repeats of this warning...]

Error: git-annex: cannot load such file -- language/haskell

I also tried running the 2nd command above with the full version number 7.[number], but that didn't change anything. Googling about that error brought me here:
https://stackoverflow.com/questions/67059691/warning-calling-sha256-digest-tag-in-a-bottle-block-is-deprecated-use
... so I ran:
brew style --fix /usr/local/Homebrew/Library/Taps/ptaylor/homebrew-local-git-annex/Formula
(I note that before running this, I checked out what the above directory looked---it was empty; after running this command, it still was.)
... but then running the above "brew extract ..." didn't produce any different output.

Any advice is welcome.

[leej3]

I'm going to leave this for now in the hope that only supporting git annex version 8 is sufficient

[mrneont]

Closing this now, because the main issue that led us down this road has been resolved by @yarikoptic; see here:
#2 (comment)