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Restore 'owned' stubbed methods only in ruby 2.3+.

gitlab-qa-bot requested to merge github/fork/jrafanie/fix_ruby22_aliased_method_stubbing into master

Created by: jrafanie

Fixes #1057 (closed).

In b94fe10e, we changed behavior to to restore 'owned' stubbed methods for all rubies.

This doesn't work for all rubies because Method#owner for aliased methods is inconsistent [1].

Since, ruby 2.3+ broke our prior backup/restore mechanism, it's safer to change the original behavior for ruby 2.3+ only.

A @klass can have methods implemented (see Method#owner) in @klass or inherited from a superclass. In ruby 2.2 and earlier, we can copy a method regardless of the 'owner' and restore it to @klass after because a call to 'super' from @klass's copied method would end up calling the original class's superclass's method.

With the commit below [2], available starting in 2.3.0, ruby changed this behavior and a call to 'super' from the method copied to @klass will call @klass's superclass method, which is the original implementer of this method! This leads to very strange errors if @klass's copied method calls 'super', since it would end up calling itself, the original method implemented in @klass's superclass.

For ruby 2.3 and above, we need to only restore methods that @klass originally owned.

[1] https://gist.github.com/jrafanie/0e5b8a9f4e8b4f84913f [2] https://github.com/ruby/ruby/commit/c8854d2ca4be9ee6946e6d17b0e17d9ef130ee81

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