[rubygems/rubygems] Let resolver consider unique specs from the beginning

It results in more consistent error messages.

https://github.com/rubygems/rubygems/commit/a4b34361cc

lib/bundler/resolver.rb

@@ -79,7 +79,7 @@ module Bundler
     def solve_versions(root:, logger:)
       solver = PubGrub::VersionSolver.new(source: self, root: root, logger: logger)
       result = solver.solve
-      result.map {|package, version| version.to_specs(package) }.flatten.uniq
+      result.map {|package, version| version.to_specs(package) }.flatten
     rescue PubGrub::SolveFailure => e
       incompatibility = e.incompatibility
 
@@ -270,6 +270,7 @@ module Bundler
         end
 
         platform_specs.flatten!
+        platform_specs.uniq!
 
         ruby_specs = select_best_platform_match(specs, Gem::Platform::RUBY)
         groups << Resolver::Candidate.new(version, specs: ruby_specs) if ruby_specs.any?

spec/bundler/commands/lock_spec.rb

@@ -1467,9 +1467,7 @@ RSpec.describe "bundle lock" do
          #{Bundler::VERSION}
     L
 
-    bundle "lock", raise_on_error: false
-
-    expect(err).to eq <<~ERR.strip
+    expected_error = <<~ERR.strip
       Could not find compatible versions
 
           Because every version of activemodel depends on activesupport = 6.0.4
@@ -1493,28 +1491,13 @@ RSpec.describe "bundle lock" do
             version solving has failed.
     ERR
 
+    bundle "lock", raise_on_error: false
+    expect(err).to eq(expected_error)
+
     lockfile lockfile.gsub(/PLATFORMS\n  #{local_platform}/m, "PLATFORMS\n  #{lockfile_platforms("ruby")}")
 
     bundle "lock", raise_on_error: false
-
-    expect(err).to eq <<~ERR.strip
-      Could not find compatible versions
-
-      Because rails >= 7.0.3.1, < 7.0.4 depends on activemodel = 7.0.3.1
-        and rails >= 7.0.2.3, < 7.0.3.1 depends on activemodel = 7.0.2.3,
-        rails >= 7.0.2.3, < 7.0.4 requires activemodel = 7.0.2.3 OR = 7.0.3.1.
-      And because every version of activemodel depends on activesupport = 6.0.4,
-        rails >= 7.0.2.3, < 7.0.4 requires activesupport = 6.0.4.
-      Because rails >= 7.0.3.1, < 7.0.4 depends on activesupport = 7.0.3.1
-        and rails >= 7.0.2.3, < 7.0.3.1 depends on activesupport = 7.0.2.3,
-        rails >= 7.0.2.3, < 7.0.4 requires activesupport = 7.0.2.3 OR = 7.0.3.1.
-      Thus, rails >= 7.0.2.3, < 7.0.4 cannot be used.
-      And because rails >= 7.0.4 depends on activemodel = 7.0.4,
-        rails >= 7.0.2.3 requires activemodel = 7.0.4.
-      So, because activemodel = 7.0.4 could not be found in rubygems repository https://gem.repo4/ or installed locally
-        and Gemfile depends on rails >= 7.0.2.3,
-        version solving has failed.
-    ERR
+    expect(err).to eq(expected_error)
   end
 
   it "does not accidentally resolves to prereleases" do