[Fetcher] Chunk API requests to stay under the request limit

Fixes #3367
Closes #3382

lib/bundler/fetcher.rb

@@ -301,10 +301,14 @@ def dependency_api_uri(gem_names = [])
     # fetch from Gemcutter Dependency Endpoint API
     def fetch_dependency_remote_specs(gem_names)
       Bundler.ui.debug "Query Gemcutter Dependency Endpoint API: #{gem_names.join(',')}"
-      marshalled_deps = fetch dependency_api_uri(gem_names)
-      gem_list = Bundler.load_marshal(marshalled_deps)
+      gem_list = []
       deps_list = []
 
+      gem_names.each_slice(Source::Rubygems::API_REQUEST_LIMIT) do |names|
+        marshalled_deps = fetch dependency_api_uri(names)
+        gem_list += Bundler.load_marshal(marshalled_deps)
+      end
+
       spec_list = gem_list.map do |s|
         dependencies = s[:dependencies].map do |name, requirement|
           dep = well_formed_dependency(name, requirement.split(", "))