Only change cloned copy version if necessary

This should make binstubs more responsive when using `ENV["RGV"]`.

1 files changed, 15 insertions, 2 deletions

diff --git a/spec/support/rubygems_version_manager.rb b/spec/support/rubygems_version_manager.rb
index 83d33da7c3..4be90f7679 100644
--- a/spec/support/rubygems_version_manager.rb
+++ b/spec/support/rubygems_version_manager.rb
@@ -15,7 +15,7 @@ class RubygemsVersionManager
 
     unrequire_rubygems_if_needed
 
-    switch_local_copy
+    switch_local_copy_if_needed
 
     prepare_environment
   end
@@ -40,7 +40,9 @@ private
     exec(ENV, *cmd)
   end
 
-  def switch_local_copy
+  def switch_local_copy_if_needed
+    return unless local_copy_switch_needed?
+
     Dir.chdir(local_copy_path) do
       sys_exec!("git remote update")
       sys_exec!("git checkout #{target_tag_version} --quiet")
@@ -55,6 +57,10 @@ private
     defined?(Gem) && Gem::VERSION != target_gem_version
   end
 
+  def local_copy_switch_needed?
+    !env_version_is_path? && target_gem_version != local_copy_version
+  end
+
   def target_gem_version
     @target_gem_version ||= resolve_target_gem_version
   end
@@ -63,6 +69,13 @@ private
     @target_tag_version ||= resolve_target_tag_version
   end
 
+  def local_copy_version
+    gemspec_contents = File.read(local_copy_path.join("lib/rubygems.rb"))
+    version_regexp = /VERSION = ["'](.*)["']/
+
+    version_regexp.match(gemspec_contents)[1]
+  end
+
   def local_copy_path
     @local_copy_path ||= resolve_local_copy_path
   end