`bundle update --bundler` doesn't update bundler version in lockfile unless older Bundler version is uninstalled

[dentarg]

Describe the problem as clearly as you can

If you have done bundle install with Bundler 2.3.3 on a lockfile with BUNDLED WITH set to 2.2.33, bundle update --bundler wont update the Bundler version unless you uninstall Bundler 2.2.33.

Post steps to reproduce the problem

$ echo 3.0.3 > .ruby-version
$ ruby -v
ruby 3.0.3p157 (2021-11-24 revision 3fb7d2cadc) [x86_64-darwin19]

$ gem list bundler

*** LOCAL GEMS ***

bundler (default: 2.2.33)

$ bundler -v
Bundler version 2.2.33

$ bundle init
Writing new Gemfile to /Users/dentarg/test/Gemfile

$ echo 'gem "dyno_metadata"' >> Gemfile

$ bundle
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies...
Using bundler 2.2.33
Using dyno_metadata 0.0.3
Bundle complete! 1 Gemfile dependency, 2 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.

$ cat Gemfile.lock
GEM
  remote: https://rubygems.org/
  specs:
    dyno_metadata (0.0.3)

PLATFORMS
  x86_64-darwin-19

DEPENDENCIES
  dyno_metadata

BUNDLED WITH
   2.2.33

$ echo 3.1.0 > .ruby-version

$ bundle
Bundler 2.3.3 is running, but your lockfile was generated with 2.2.33. Installing Bundler 2.2.33 and restarting using that version.
Calling `DidYouMean::SPELL_CHECKERS.merge!(error_name => spell_checker)' has been deprecated. Please call `DidYouMean.correct_error(error_name, spell_checker)' instead.
Using bundler 2.2.33
Using dyno_metadata 0.0.3
Bundle complete! 1 Gemfile dependency, 2 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.

$ cat Gemfile.lock
GEM
  remote: https://rubygems.org/
  specs:
    dyno_metadata (0.0.3)

PLATFORMS
  x86_64-darwin-19

DEPENDENCIES
  dyno_metadata

BUNDLED WITH
   2.2.33

$ bundle update --bundler
Calling `DidYouMean::SPELL_CHECKERS.merge!(error_name => spell_checker)' has been deprecated. Please call `DidYouMean.correct_error(error_name, spell_checker)' instead.
Using bundler 2.2.33
Using dyno_metadata 0.0.3
Bundle updated!

$ grep -A1 'BUNDLED WITH' Gemfile.lock
BUNDLED WITH
   2.2.33

$ gem uninstall bundler -v 2.2.33
Successfully uninstalled bundler-2.2.33

$ bundle update --bundler
Using bundler 2.3.3
Using dyno_metadata 0.0.3
Bundle updated!

$ grep -A1 'BUNDLED WITH' Gemfile.lock
BUNDLED WITH
   2.3.3

What were you expecting to happen?

Be able to update the Bundler version in the lockfile without uninstalling older Bundler version.

What actually happened?

Bundler version in lockfile wasn't updated.

[dentarg]

Maybe #5182 will solve this?

[deivid-rodriguez]

This was fixed by #5224, I will release it soon. In the mean time, you can workaround bundle _2.3.3_ update --bundler, or indeed like you did by uninstalling the locked version.

I'm sorry, the warning in #5234 plus this regression was a very unfortunate combo :(

[SampsonCrowley]

just an FYI 2.4.22 still had this issue running bundle _2.4.22_ update --bundler

I know it's old, but a LOT of enterprise systems have outdated software, and updating involves first updating to the newest version you can get things to without breaking; which in our case is Ruby 2.7.10 and Bundler 2.4.22 as the step before Ruby 3

I had to just manually change the BUNDLED WITH version