My personal view is that given recent events, if contributing to a project requires signing a CLA with a company (instead of an independent organization) then you should only contribute to the project if you're getting paid for it. For example, if your employer wants you to send in bug fixes so you don't have to maintain them. This may be a bit strong, but executing a CLA outside your employer's eye may be legally hazardous anyway in a 'we own all the work you do anywhere' environment.