Log Message:
Update ruby-mocha to 1.2.1.

## 1.2.1

* Fixed #272. Workaround Ruby bug 12832 which caused interpreter to hang. See \ 
https://bugs.ruby-lang.org/issues/12832. Thanks to @chrisroos & @petems \ 
(6f1c8b9b, #273).

## 1.2.0

* Always use prepended module to stub class & instance methods for Ruby v2+ \ 
- thanks to @grosser & @chrisroos (43d56671, #244)
* Always use prepended module to stub AnyInstance methods in Ruby v2+ - thanks \ 
to @chrisroos (#262)
* Always set visibility of stub method to match stubbed method on included \ 
module - thanks to @grosser & @chrisroos (e87c03b0, #248)
* Always set visibility to stub method to match stubbed method on superclass - \ 
thanks to @chrisroos (38d902ad)
* Allow stubbing of method to which any instance responds (#200)
* Allow `includes` matcher to take matcher arguments - thanks to @lazyatom (#217)
* Avoid exception in older version of Rubygems - thanks to @chrisroos (78d930a7)
* Add licenses to gemspec as requested by @coreyhaines (#201)
* Fix typo in README - thanks to @jaredbeck (6119460d)
* Added section about using Mocha with RSpec & Rails to README (#221)
* Fix documentation for Mocha::API#stub method - thanks to @raeno (599b1dcd)
* Added backers and sponsors from OpenCollective - thanks to @piamancini (#253)
* Fix typo in docs for equals - thanks to @alexcoco (#254)
* Add known issue for Ruby v1.8 to README - thanks to @chrisroos (2c642096)