Improve error message when `include` is blocked

lib/gitlab/ci/config/external/file/remote.rb

@@ -31,14 +31,12 @@ module Gitlab
                 errors.push("Remote file `#{location}` could not be fetched because of a timeout error!")
               rescue Gitlab::HTTP::Error
                 errors.push("Remote file `#{location}` could not be fetched because of HTTP error!")
-              rescue Gitlab::HTTP::BlockedUrlError
-                errors.push("Remote file `#{location}` could not be fetched because the URL is blocked!")
+              rescue Gitlab::HTTP::BlockedUrlError => e
+                errors.push("Remote file could not be fetched because #{e}!")
               end
 
               if response&.code.to_i >= 400
-                errors.push <<~ERROR
-                  Remote file `#{location}` could not be fetched because of HTTP code `#{response.code}` error!
-                ERROR
+                errors.push("Remote file `#{location}` could not be fetched because of HTTP code `#{response.code}` error!")
               end
 
               response.to_s if errors.none?

spec/lib/gitlab/ci/config/external/file/remote_spec.rb

@@ -144,5 +144,14 @@ describe Gitlab::Ci::Config::External::File::Remote do
         expect(subject).to match /could not be fetched because of HTTP code `404` error!/
       end
     end
+
+    context 'when the URL is blocked' do
+      let(:location) { 'http://127.0.0.1/some/path/to/config.yaml' }
+
+      it 'should include details about blocked URL' do
+        expect(subject).to eq "Remote file could not be fetched because URL '#{location}' " \
+                              'is blocked: Requests to localhost are not allowed!'
+      end
+    end
   end
 end