I believe the pro-sites has a bug in the function 'is_pro_site'

This function is being referenced by the domain mapping plugin, however it is giving an un-expected result.

Please refer to the post:

https://premium.wpmudev.org/forums/topic/domain-mapping-menu-not-showing-up-in-sites#post-645687

I believe the issue is cause by the function: is_pro_site

which is located on line 955 in pro-sites/pro-sites.php

Would love to know if this is bug, and if it has the potential to cause other issues.

Thanks!