fix BUNDLE_LOCKFILE=Gemfile.lock

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    bundler-multilock (1.1.1)
+    bundler-multilock (1.1.2)
       bundler (~> 2.4.19)
 
 GEM

lib/bundler/multilock.rb

@@ -62,14 +62,8 @@ def add_lockfile(lockfile = nil,
           raise ArgumentError, "Lockfile #{lockfile} is already defined"
         end
 
-        env_lockfile = ENV["BUNDLE_LOCKFILE"]
-        if env_lockfile
-          unless env_lockfile.include?("/") || env_lockfile.end_with?(".lock")
-            env_lockfile = "Gemfile.#{env_lockfile}.lock"
-          end
-          env_lockfile = Bundler.root.join(env_lockfile).expand_path
-          active = env_lockfile == lockfile
-        end
+        env_lockfile = ENV["BUNDLE_LOCKFILE"]&.then { |l| expand_lockfile(l) }
+        active = env_lockfile == lockfile if env_lockfile
 
         if active && (old_active = lockfile_definitions.find { |definition| definition[:active] })
           raise ArgumentError, "Only one lockfile (#{old_active[:lockfile]}) can be flagged as the default"
@@ -310,16 +304,17 @@ def loaded!
 
         return unless lockfile_definitions.none? { |definition| definition[:active] }
 
-        # Gemfile.lock isn't explicitly specified, otherwise it would be active
-        default_lockfile_definition = lockfile_definitions.find do |definition|
-          definition[:lockfile] == Bundler.default_lockfile(force_original: true)
-        end
-        if ENV["BUNDLE_LOCKFILE"] == Bundler.default_lockfile(force_original: true) && default_lockfile_definition
+        if ENV["BUNDLE_LOCKFILE"]&.then { |l| expand_lockfile(l) } ==
+           Bundler.default_lockfile(force_original: true)
           return
         end
 
         raise GemfileNotFound, "Could not locate lockfile #{ENV["BUNDLE_LOCKFILE"].inspect}" if ENV["BUNDLE_LOCKFILE"]
 
+        # Gemfile.lock isn't explicitly specified, otherwise it would be active
+        default_lockfile_definition = lockfile_definitions.find do |definition|
+          definition[:lockfile] == Bundler.default_lockfile(force_original: true)
+        end
         return unless default_lockfile_definition && default_lockfile_definition[:active] == false
 
         raise GemfileEvalError, "No lockfiles marked as default"

lib/bundler/multilock/version.rb

@@ -2,6 +2,6 @@
 
 module Bundler
   module Multilock
-    VERSION = "1.1.1"
+    VERSION = "1.1.2"
   end
 end

spec/bundler/multilock_spec.rb

@@ -620,6 +620,18 @@
     end
   end
 
+  it "allows explicitly specifying the default lockfile" do
+    with_gemfile(<<~RUBY) do
+      gem "rake"
+
+      lockfile("alt1") do
+        gem "concurrent-ruby", "1.2.1"
+      end
+    RUBY
+      invoke_bundler("install", env: { "BUNDLE_LOCKFILE" => "Gemfile.lock" })
+    end
+  end
+
   # so that it won't downgrade if that's all you have available
   it "installs missing deps from alternate lockfiles before syncing" do
     Bundler.with_unbundled_env do