https://github.com/pypa/pip/pull/374

The pull request addresses a UnicodeDecodeError bug in pip. It affects pip in Python 3 and it’s triggered when a package install fails and emits Unicode characters to the console. A classic case of this are gcc error messages which use exotic quotes.

It adds a test for the issue and then fixes it. Fixing this also required making a fix to Ian Bicking’s ScriptTest package, which was incorporated in ScriptTest 1.2.

The pip fix has not been included in an official pip release yet.