bundle update --bundler

had to fix command detection, since with 2.5.10, CLI::Install is
_always_ required for the new auto-install feature

.github/workflows/ci.yml

@@ -14,12 +14,12 @@ jobs:
       fail-fast: false
       matrix:
         ruby-version: [2.6, 2.7, "3.0", 3.1, 3.2]
-        bundler-version: [2.4.19, 2.4.22, 2.5.9]
+        bundler-version: [2.4.19, 2.4.22, 2.5.10]
         exclude:
           - ruby-version: 2.6
-            bundler-version: 2.5.9
+            bundler-version: 2.5.10
           - ruby-version: 2.7
-            bundler-version: 2.5.9
+            bundler-version: 2.5.10
     env:
       BUNDLER_VERSION: ${{ matrix.bundler-version }}
       BUNDLE_LOCKFILE: active

Gemfile.lock

@@ -102,4 +102,4 @@ DEPENDENCIES
   stringio (~> 3.1)
 
 BUNDLED WITH
-   2.5.9
+   2.5.10

Gemfile.ruby-2.6.lock

@@ -50,4 +50,4 @@ DEPENDENCIES
   stringio (= 3.0.6)
 
 BUNDLED WITH
-   2.5.9
+   2.5.10

lib/bundler/multilock.rb

@@ -82,18 +82,17 @@ def add_lockfile(lockfile = nil,
           enforce_pinned_additional_dependencies: enforce_pinned_additional_dependencies
         })
 
-        if (defined?(CLI::Check) ||
-            defined?(CLI::Install) ||
-            defined?(CLI::Lock) ||
-            defined?(CLI::Update)) &&
-           !defined?(CLI::Cache) && !env_lockfile
-          # always use Gemfile.lock for `bundle check`, `bundle install`,
-          # `bundle lock`, and `bundle update`. `bundle cache` delegates to
-          # `bundle install`, but we want that to run as normal.
-          # If they're using BUNDLE_LOCKFILE, then they really do want to
-          # use a particular lockfile, and it overrides whatever they
-          # dynamically set in their gemfile
-          active = lockfile == Bundler.default_lockfile(force_original: true)
+        # If they're using BUNDLE_LOCKFILE, then they really do want to
+        # use a particular lockfile, and it overrides whatever they
+        # dynamically set in their gemfile
+        unless env_lockfile
+          # this is a little icky, but there's no other way to determine which command was run
+          cli = ObjectSpace.each_object(CLI).first
+          if %i[check install lock update].include?(cli&.current_command_chain&.first)
+            # always use Gemfile.lock for `bundle check`, `bundle install`,
+            # `bundle lock`, and `bundle update`.
+            active = lockfile == Bundler.default_lockfile(force_original: true)
+          end
         end
 
         if active