A fix for issues #3089, #3216 and #3248

Currently Bundler is aggressive to try different
versions of exsiting gem parents before
exhausting different versions of parents of
current conflicting gem.

By making sure we travase the current conflicting
dependency tree before trying to make use of exsiting
(activated) gem dependency tree, we reduce the number of
conflicts and activation of gems older then the latest
compitable version.

However, a long term solution would be to make the resolver smarter
by making it understand if current requirement conflict is caused by
either by it's parent or existing gem parent by looking at each of their
dependency requirements.

1 files changed, 6 insertions, 3 deletions

diff --git a/lib/bundler/resolver.rb b/lib/bundler/resolver.rb
index 7c4a10482e..f44e03a60e 100644
--- a/lib/bundler/resolver.rb
+++ b/lib/bundler/resolver.rb
@@ -171,13 +171,16 @@ module Bundler
     end
 
     def handle_conflict(current, states, existing=nil)
-      until current.nil? && existing.nil?
+      until current.nil?
         current_state = find_state(current, states)
-        existing_state = find_state(existing, states)
         return current if state_any?(current_state)
+        current = current.required_by.last if current
+      end
+
+      until existing.nil?
+        existing_state = find_state(existing, states)
         return existing if state_any?(existing_state)
         existing = existing.required_by.last if existing
-        current = current.required_by.last if current
       end
     end