Fix a sed portability issue
Fix a sed portability issue

In 31b5ea7dacbd7c83874e1e6a9da7e7b49ccfd048 we fixed one sed portability
issue introduced in #2831. Here's another.

mccolgst/www.gittip.com,gratipay/gratipay.com,eXcomm/gratipay.com,mccolgst/www.gittip.com,gratipay/gratipay.com,studio666/gratipay.com,studio666/gratipay.com,studio666/gratipay.com,eXcomm/gratipay.com,gratipay/gratipay.com,eXcomm/gratipay.com,gratipay/gratipay.com,mccolgst/www.gittip.com,mccolgst/www.gittip.com,eXcomm/gratipay.com,studio666/gratipay.com