Merge pull request #7353 from dnkoutso/uniq_prerelease_versions

Unique all available pre-release versions when displaying

CHANGELOG.md

@@ -18,6 +18,10 @@ To install release candidates run `[sudo] gem install cocoapods --pre`
 
 ##### Bug Fixes
 
+* Unique all available pre-release versions when displaying  
+  [Samuel Giddins](https://github.com/segiddins)
+  [#7353](https://github.com/CocoaPods/CocoaPods/pull/7353)
+
 * Do not attempt compilation for pods with no sources and skipping import validation  
   [Dimitris Koutsogiorgas](https://github.com/dnkoutso)
   [#7336](https://github.com/CocoaPods/CocoaPods/issues/7336)

lib/cocoapods/resolver.rb

@@ -477,7 +477,7 @@ module Pod
               # Conflict was caused by not specifying an explicit version for the requirement #[name],
               # and there is no available stable version satisfying constraints for the requirement.
               o << "\nThere are only pre-release versions available satisfying the following requirements:\n"
-              conflict.requirements.values.flatten.each do |r|
+              conflict.requirements.values.flatten.uniq.each do |r|
                 unless search_for(r).empty?
                   o << "\n\t'#{name}', '#{r.requirement}'\n"
                 end