Homebrew builds from GitHub archives

docs/homebrew.md

@@ -60,5 +60,5 @@ brew update-python-resources Formula/roll.rb
 ## Notes for `roll`
 
 - `rl update` intentionally does not self-update. Homebrew users should use `brew upgrade roll`.
-- package versioning is configured to work from git archives used by tagged source tarballs.
+- the formula exports `SETUPTOOLS_SCM_PRETEND_VERSION_FOR_ROLL`, so Homebrew does not depend on git metadata surviving the GitHub archive step.
 - a meaningful `brew test` should initialize a temporary archive and verify that `.roll` was created.

packaging/homebrew/roll.rb

@@ -20,6 +20,9 @@ class Roll < Formula
   end
 
   def install
+    # GitHub source archives do not reliably preserve enough VCS metadata for
+    # setuptools-scm, so pin the package version from the formula itself.
+    ENV["SETUPTOOLS_SCM_PRETEND_VERSION_FOR_ROLL"] = version.to_s
     virtualenv_install_with_resources
   end