[rubygems/rubygems] Rename `BUNDLE_SPEC_RUN` environment variable

The `BUNDLE_` prefix should be reserved to first class settings that
should be listed when running `bundle config`. This one is just a hacky
environment variable that has not corresponding documented setting.

https://github.com/rubygems/rubygems/commit/7e255c5058

lib/bundler/shared_helpers.rb

@@ -239,7 +239,7 @@ module Bundler
       current  = File.expand_path(SharedHelpers.pwd).tap{|x| x.untaint if RUBY_VERSION < "2.7" }
 
       until !File.directory?(current) || current == previous
-        if ENV["BUNDLE_SPEC_RUN"]
+        if ENV["BUNDLER_SPEC_RUN"]
           # avoid stepping above the tmp directory when testing
           gemspec = if ENV["GEM_COMMAND"]
             # for Ruby Core

spec/bundler/commands/config_spec.rb

@@ -425,27 +425,27 @@ E
 
   describe "subcommands" do
     it "list" do
-      bundle "config list"
-      expect(out).to eq "Settings are listed in order of priority. The top value will be used.\nspec_run\nSet via BUNDLE_SPEC_RUN: \"true\""
+      bundle "config list", :env => { "BUNDLE_FOO" => "bar" }
+      expect(out).to eq "Settings are listed in order of priority. The top value will be used.\nfoo\nSet via BUNDLE_FOO: \"bar\""
 
-      bundle "config list", :parseable => true
-      expect(out).to eq "spec_run=true"
+      bundle "config list", :env => { "BUNDLE_FOO" => "bar" }, :parseable => true
+      expect(out).to eq "foo=bar"
     end
 
     it "list with credentials" do
       bundle "config list", :env => { "BUNDLE_GEMS__MYSERVER__COM" => "user:password" }
-      expect(out).to eq "Settings are listed in order of priority. The top value will be used.\ngems.myserver.com\nSet via BUNDLE_GEMS__MYSERVER__COM: \"user:[REDACTED]\"\n\nspec_run\nSet via BUNDLE_SPEC_RUN: \"true\""
+      expect(out).to eq "Settings are listed in order of priority. The top value will be used.\ngems.myserver.com\nSet via BUNDLE_GEMS__MYSERVER__COM: \"user:[REDACTED]\""
 
       bundle "config list", :parseable => true, :env => { "BUNDLE_GEMS__MYSERVER__COM" => "user:password" }
-      expect(out).to eq "gems.myserver.com=user:password\nspec_run=true"
+      expect(out).to eq "gems.myserver.com=user:password"
     end
 
     it "list with API token credentials" do
       bundle "config list", :env => { "BUNDLE_GEMS__MYSERVER__COM" => "api_token:x-oauth-basic" }
-      expect(out).to eq "Settings are listed in order of priority. The top value will be used.\ngems.myserver.com\nSet via BUNDLE_GEMS__MYSERVER__COM: \"[REDACTED]:x-oauth-basic\"\n\nspec_run\nSet via BUNDLE_SPEC_RUN: \"true\""
+      expect(out).to eq "Settings are listed in order of priority. The top value will be used.\ngems.myserver.com\nSet via BUNDLE_GEMS__MYSERVER__COM: \"[REDACTED]:x-oauth-basic\""
 
       bundle "config list", :parseable => true, :env => { "BUNDLE_GEMS__MYSERVER__COM" => "api_token:x-oauth-basic" }
-      expect(out).to eq "gems.myserver.com=api_token:x-oauth-basic\nspec_run=true"
+      expect(out).to eq "gems.myserver.com=api_token:x-oauth-basic"
     end
 
     it "get" do

spec/bundler/spec_helper.rb

@@ -71,7 +71,7 @@ RSpec.configure do |config|
 
     require_relative "support/rubygems_ext"
     Spec::Rubygems.test_setup
-    ENV["BUNDLE_SPEC_RUN"] = "true"
+    ENV["BUNDLER_SPEC_RUN"] = "true"
     ENV["BUNDLE_USER_CONFIG"] = ENV["BUNDLE_USER_CACHE"] = ENV["BUNDLE_USER_PLUGIN"] = nil
     ENV["RUBYGEMS_GEMDEPS"] = nil
     ENV["XDG_CONFIG_HOME"] = nil