exit with a non-zero exit code when git pull --ff-only fails instead of just showing a warning

CHANGELOG.md

@@ -16,6 +16,11 @@ To install release candidates run `[sudo] gem install cocoapods --pre`
   [Danielle Tomlinson](https://github.com/dantoml)
   [#6042](https://github.com/CocoaPods/CocoaPods/pull/6042)
 
+* Exit with non-zero exit status if pod repo update fails
+  [Uku Loskit](https://github.com/UkuLoskit)
+  [#6037](https://github.com/CocoaPods/CocoaPods/issues/6037)
+
+
 ##### Bug Fixes
 
 * None.  

lib/cocoapods/sources_manager.rb

@@ -107,10 +107,10 @@ module Pod
         git!(['-C', repo, 'pull', '--ff-only'])
       end
     rescue
-      UI.warn 'CocoaPods was not able to update the ' \
-                "`#{name}` repo. If this is an unexpected issue " \
-                'and persists you can inspect it running ' \
-                '`pod repo update --verbose`'
+      raise Informative, 'CocoaPods was not able to update the ' \
+        "`#{name}` repo. If this is an unexpected issue " \
+        'and persists you can inspect it running ' \
+        '`pod repo update --verbose`'
     end
   end
 

spec/unit/sources_manager_spec.rb

@@ -135,9 +135,8 @@ fatal: Could not read from remote repository.
 Please make sure you have the correct access rights
 and the repository exists.
         EOS
-        @sources_manager.expects(:update_search_index_if_needed_in_background).with({}).returns(nil)
-        @sources_manager.update(test_repo_path.basename.to_s, true)
-        UI.warnings.should.include('not able to update the `master` repo')
+        e = lambda { @sources_manager.update(test_repo_path.basename.to_s, true) }.should.raise Pod::Informative
+        e.message.should.include('not able to update the `master` repo')
       end
 
       it 'informs the user if there is an update for CocoaPods' do