Unreachable URL incorrectly marked as "Unsupported protocol"

Selecting a Subversion repository at https://bitbucket.org/repo/import gives me the following clientside errors:

• Not a valid URL.
• Unsupported protocol. Please use 'http://', 'https://' , 'svn://' or 'git://.'

The site URL is in the following format (but every format seems to fail): https://svn.COMPANYNAME.net/Clients/COMPANYNAME/web/tools/CodeGen