Performance: lazily memoize expensive `prerelease?` values during resolve

Conflicts:
	lib/bundler/resolver.rb

1 files changed, 2 insertions, 1 deletions

diff --git a/lib/bundler/resolver.rb b/lib/bundler/resolver.rb
index 7c4a10482e..218a69969d 100644
--- a/lib/bundler/resolver.rb
+++ b/lib/bundler/resolver.rb
@@ -140,6 +140,7 @@ module Bundler
       @index                = index
       @deps_for             = {}
       @missing_gems         = Hash.new(0)
+      @prereleases_cache    = Hash.new { |h,k| h[k] = k.prerelease? }
       @source_requirements  = source_requirements
       @iteration_counter    = 0
       @started_at           = Time.now
@@ -264,7 +265,7 @@ module Bundler
 
         reqs = reqs.sort_by do |a|
           [ activated[a.name] ? 0 : 1,
-            a.requirement.prerelease? ? 0 : 1,
+            @prereleases_cache[a.requirement] ? 0 : 1,
             @errors[a.name]   ? 0 : 1,
             activated[a.name] ? 0 : @gems_size[a] ]
         end