Using bundlerEnv with the gem kubeclient fails with a NameError

[shuhaowu]

Describe the bug
Creating a bundlerEnv with the gem kubeclient and attempting to require "kubeclient" causes a NameError to be raised upon require.

To Reproduce
Steps to reproduce the behavior:

1. A minimal example with shell.nix, gemset.nix and Gemfile is available here: https://gist.github.com/shuhaowu/0c54e9051d41ff4b348486793ae6fcd2. In case that becomes unavailable in the future, here's a zipfile of it.
2. Run nix-shell with the above environment.
3. Run irb, and in it, run require 'kubeclient'

Immediately, you will see:

/nix/store/r84snw8z4zr3fhaai4cs8j19lgkv76si-ruby2.6.5-http-accept-1.7.0/lib/ruby/gems/2.6.0/gems/http-accept-1.7.0/lib/http/accept/version.rb:23: warning: already initialized constant HTTP::Accept::VERSION
/nix/store/04zfivb2qpnfmz8xk3pg24l3r8qd9s0y-testenv/lib/ruby/gems/2.6.0/gems/http-accept-1.7.0/lib/http/accept/version.rb:23: warning: previous definition of VERSION was here
Traceback (most recent call last):
       16: from /nix/store/a3wafb77xrn5wcz21sxg8l40kdlm2wny-ruby-2.6.5/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:156:in `require'
       15: from /nix/store/a3wafb77xrn5wcz21sxg8l40kdlm2wny-ruby-2.6.5/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:168:in `rescue in require'
       14: from /nix/store/a3wafb77xrn5wcz21sxg8l40kdlm2wny-ruby-2.6.5/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:168:in `require'
       13: from /nix/store/bv5cb3n2wsrgf7xkr8j5qn0gyjc8kl9x-ruby2.6.5-kubeclient-4.6.0/lib/ruby/gems/2.6.0/gems/kubeclient-4.6.0/lib/kubeclient.rb:16:in `<top (required)>'
       12: from /nix/store/a3wafb77xrn5wcz21sxg8l40kdlm2wny-ruby-2.6.5/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:72:in `require'
       11: from /nix/store/a3wafb77xrn5wcz21sxg8l40kdlm2wny-ruby-2.6.5/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:72:in `require'
       10: from /nix/store/04zfivb2qpnfmz8xk3pg24l3r8qd9s0y-testenv/lib/ruby/gems/2.6.0/gems/kubeclient-4.6.0/lib/kubeclient/watch_stream.rb:2:in `<top (required)>'
        9: from /nix/store/a3wafb77xrn5wcz21sxg8l40kdlm2wny-ruby-2.6.5/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:155:in `require'
        8: from /nix/store/a3wafb77xrn5wcz21sxg8l40kdlm2wny-ruby-2.6.5/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:155:in `require'
        7: from /nix/store/lx1qgbkkmi2954i5yvzvapmff2blyycp-ruby2.6.5-http-4.4.0/lib/ruby/gems/2.6.0/gems/http-4.4.0/lib/http.rb:14:in `<top (required)>'
        6: from /nix/store/a3wafb77xrn5wcz21sxg8l40kdlm2wny-ruby-2.6.5/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:72:in `require'
        5: from /nix/store/a3wafb77xrn5wcz21sxg8l40kdlm2wny-ruby-2.6.5/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:72:in `require'
        4: from /nix/store/04zfivb2qpnfmz8xk3pg24l3r8qd9s0y-testenv/lib/ruby/gems/2.6.0/gems/http-4.4.0/lib/http/response.rb:11:in `<top (required)>'
        3: from /nix/store/a3wafb77xrn5wcz21sxg8l40kdlm2wny-ruby-2.6.5/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:72:in `require'
        2: from /nix/store/a3wafb77xrn5wcz21sxg8l40kdlm2wny-ruby-2.6.5/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:72:in `require'
        1: from /nix/store/04zfivb2qpnfmz8xk3pg24l3r8qd9s0y-testenv/lib/ruby/gems/2.6.0/gems/http-cookie-1.0.3/lib/http/cookie_jar.rb:8:in `<top (required)>'
NameError (uninitialized constant HTTP::CookieJar)

Expected behavior
Expect the ruby module to be imported correctly.

Additional context
The warnings complaining about already initialized constants suggests that certain files are being required twice.

Metadata

these paths will be fetched (0.00 MiB download, 0.00 MiB unpacked):
  /nix/store/8pkkw458w4q00gp9yrcg95mxc72nzd85-nix-info
copying path '/nix/store/8pkkw458w4q00gp9yrcg95mxc72nzd85-nix-info' from 'https://cache.nixos.org'...
 - system: `"x86_64-linux"`
 - host os: `Linux 5.0.0-1033-gcp, Ubuntu, 18.04.4 LTS (Bionic Beaver)`
 - multi-user?: `no`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.3.3`
 - channels(shuhao): `"nixpkgs-20.09pre217526.9b3515eb95d"`
 - nixpkgs: `/home/shuhao/.nix-defexpr/channels/nixpkgs`

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute:
# a list of nixos modules affected by the problem
module:

[burke]

FWIW, we work around this by requiring nix_store_safeguard.rb with RUBYOPT, but the solution is... suboptimal. I wonder if there's some alternative strategy that doesn't involve symlinking code (but also doesn't wastefully copy it all).

[stale]

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[lilyball]

If this is the issue I think it is, it can also be solved by copying all gemfiles instead of symlinking them. Which is also suboptimal but better than monkeypatching. With bundlerEnv you can do this by passing copyGemFiles = true. Unfortunately if you use bundlerApp there's no current parameter for this.

[shuhaowu]

Can confirm the above solves the issue. I observed another case today where if i require "minitest" twice, the second time will double include and cause some exceptions.