The PR that added this #8622 didn't actually resolve the problem because you see the warning when the `@ref_type` you've specified is a `:revision` (not a `:branch` or `:tag`).
The output looks like this:
```
==> Checking out revision 3b3527f5050270cf1acd280691b09b5abe130e73
Note: switching to '3b3527f5050270cf1acd280691b09b5abe130e73'
You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by switching back to a branch.
If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -c with the switch command. Example:
git switch -c <new-branch-name>
Or undo this operation with:
git switch -
Turn off this advice by setting config variable advice.detachedHead to false
```
Given a formula with a broken build, if you install it locally with `brew install path/to/formula.rb`, when the build fails, Homebrew will attempt to [search for open issues on the tap](073c4177b5/Library/Homebrew/exceptions.rb (L489)); but in this case `formula.tap` is `nil` and `tap.full_name` would raise a `NoMethodError` yielding this output:
```
$ brew install ./erg.rb
Error: Failed to load cask: ./erg.rb
Cask 'erg' is unreadable: wrong constant name #<Class:0x00007fd89b246cd0>
Warning: Treating ./erg.rb as a formula.
==> Downloading https://github.com/square/erg/archive/v1.1.1.tar.gz
Already downloaded: /Users/lail/Library/Caches/Homebrew/downloads/54e3fce84302901d76d50b53aa7fe760cfcf81c9842a232d6b29e771de6ec9c5--erg-1.1.1.tar.gz
Warning: Cannot verify integrity of '54e3fce84302901d76d50b53aa7fe760cfcf81c9842a232d6b29e771de6ec9c5--erg-1.1.1.tar.gz'.
No checksum was provided for this resource.
For your reference, the checksum is:
sha256 "8dbcff3dfd67b8f6e8f2dfd4f57cf818ce0cd6ce4b52566611e698fc8778507f"
==> go get github.com/square/erg
Last 15 lines from /Users/lail/Library/Logs/Homebrew/erg/01.go:
2021-12-02 16:45:31 +0000
go
get
github.com/square/erg
go: downloading github.com/square/erg v1.2.1
go: downloading vbom.ml/util v0.0.3
go: downloading vbom.ml/util/sortorder v1.0.2
go: downloading github.com/square/grange v0.0.0-20201015231752-48d66acdd125
go: downloading github.com/deckarep/golang-set v0.0.0-20170202203032-fc8930a5e645
go: downloading github.com/fvbommel/sortorder v1.0.1
go: downloading github.com/orcaman/concurrent-map v0.0.0-20160823150647-8bf1e9bacbf6
github.com/square/erg imports
vbom.ml/util/sortorder: cannot find module providing package vbom.ml/util/sortorder
Do not report this issue to Homebrew/brew or Homebrew/core!
/usr/local/Homebrew/Library/Homebrew/utils/github.rb:64:in `issues_for_formula': undefined method `full_name' for nil:NilClass (NoMethodError)
from /usr/local/Homebrew/Library/Homebrew/exceptions.rb:489:in `fetch_issues'
from /usr/local/Homebrew/Library/Homebrew/exceptions.rb:485:in `issues'
from /usr/local/Homebrew/Library/Homebrew/exceptions.rb:539:in `dump'
from /usr/local/Homebrew/Library/Homebrew/brew.rb:155:in `rescue in <main>'
from /usr/local/Homebrew/Library/Homebrew/brew.rb:143:in `<main>'
/usr/local/Homebrew/Library/Homebrew/formula.rb:2306:in `block in system': Failed executing: go get github.com/square/erg (BuildError)
from /usr/local/Homebrew/Library/Homebrew/formula.rb:2242:in `open'
from /usr/local/Homebrew/Library/Homebrew/formula.rb:2242:in `system'
from /Users/lail/Code/homebrew-formulas/erg.rb:13:in `install'
from /usr/local/Homebrew/Library/Homebrew/build.rb:172:in `block (3 levels) in install'
from /usr/local/Homebrew/Library/Homebrew/utils.rb:588:in `with_env'
from /usr/local/Homebrew/Library/Homebrew/build.rb:134:in `block (2 levels) in install'
from /usr/local/Homebrew/Library/Homebrew/formula.rb:1297:in `block in brew'
from /usr/local/Homebrew/Library/Homebrew/formula.rb:2472:in `block (2 levels) in stage'
from /usr/local/Homebrew/Library/Homebrew/utils.rb:588:in `with_env'
from /usr/local/Homebrew/Library/Homebrew/formula.rb:2471:in `block in stage'
from /usr/local/Homebrew/Library/Homebrew/resource.rb:126:in `block (2 levels) in unpack'
from /usr/local/Homebrew/Library/Homebrew/download_strategy.rb:115:in `chdir'
from /usr/local/Homebrew/Library/Homebrew/download_strategy.rb:115:in `chdir'
from /usr/local/Homebrew/Library/Homebrew/download_strategy.rb:102:in `stage'
from /usr/local/Homebrew/Library/Homebrew/resource.rb:122:in `block in unpack'
from /usr/local/Homebrew/Library/Homebrew/mktemp.rb:63:in `block in run'
from /usr/local/Homebrew/Library/Homebrew/mktemp.rb:63:in `chdir'
from /usr/local/Homebrew/Library/Homebrew/mktemp.rb:63:in `run'
from /usr/local/Homebrew/Library/Homebrew/resource.rb:208:in `mktemp'
from /usr/local/Homebrew/Library/Homebrew/resource.rb:121:in `unpack'
from /usr/local/Homebrew/Library/Homebrew/resource.rb:96:in `stage'
from /usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.6.8/lib/ruby/2.6.0/forwardable.rb:230:in `stage'
from /usr/local/Homebrew/Library/Homebrew/formula.rb:2451:in `stage'
from /usr/local/Homebrew/Library/Homebrew/formula.rb:1290:in `brew'
from /usr/local/Homebrew/Library/Homebrew/build.rb:129:in `block in install'
from /usr/local/Homebrew/Library/Homebrew/utils.rb:588:in `with_env'
from /usr/local/Homebrew/Library/Homebrew/build.rb:124:in `install'
from /usr/local/Homebrew/Library/Homebrew/build.rb:224:in `<main>'
```
PyOxidizer downloads pre-built versions of Rust and Python, and embeds
this Python into the binaries it produces.
This goes against a number of our packaging policies, so let's make sure
formulae in Homebrew/core don't do this.
See Homebrew/homebrew-core#90025.
We upgrade dependents of upgraded formulae to make sure that an upgrade
doesn't break anything. However, this reasoning applies only when a
dependent is bottled, since attempting a source build is just as likely
to break things, if not more.
I've opted not to restrict this to, say, users only on outdated versions
of macOS in order to cleanly handle other cases where this change should
also apply: Linux, or current versions of macOS in a non-default prefix.
