[PodspecSource] Rescue HTTPError exceptions and handle them

CHANGELOG.md

@@ -42,6 +42,11 @@ To install release candidates run `[sudo] gem install cocoapods --pre`
   [Hugo Tunius](https://github.com/K0nserv)
   [#2579](https://github.com/CocoaPods/CocoaPods/issues/2579)
 
+* Any errors which occur during fetching of external podspecs over HTTP
+  will now be gracefully handled.  
+  [Hugo Tunius](https://github.com/K0nserv)
+  [#2823](https://github.com/CocoaPods/CocoaPods/issues/2823)
+
 
 ## 0.36.0.beta.1
 

lib/cocoapods/external_sources/podspec_source.rb

@@ -11,7 +11,12 @@ module Pod
         UI.titled_section(title,  :verbose_prefix => '-> ') do
           is_json = podspec_uri.split('.').last == 'json'
           require 'open-uri'
+          begin
             open(podspec_uri) { |io| store_podspec(sandbox, io.read, is_json) }
+          rescue OpenURI::HTTPError => e
+            status = e.io.status.join(' ')
+            raise Informative, "Failed to fetch podspec for `#{name}` at #{podspec_uri}. Error: #{status}"
+          end
         end
       end