$ ./pants help-advanced archive-fetcher | grep -A12 matchers
--archive-fetcher-matchers=<mapping> (default: { 'github\.com/(?P<user>[^/]+)/(?P<repo>[^/]+)':'UrlInfo(url_format=u'<https://github.com/\\g<user>/\\g<repo>/archive/{rev}.tar.gz>', default_rev=u'master', strip_level=1)','bitbucket\.org/(?P<user>[^/]+)/(?P<repo>[^/]+)':'UrlInfo(url_format=u'<https://bitbucket.org/\\g<user>/\\g<repo>/get/{rev}.tar.gz>', default_rev=u'tip', strip_level=1)','golang\.org/x/(?P<repo>[^/]+)':'UrlInfo(url_format=u'<https://github.com/golang/\\g<repo>/archive/{rev}.tar.gz>', default_rev=u'master', strip_level=1)' })
    A mapping from a remote import path matching regex to an UrlInfo struct
    describing how to fetch and unpack a remote import path.  The regex must
    match the beginning of the remote import path; no '^' anchor is needed, it
    is assumed. The UrlInfo struct is a 3-tuple with the following slots: 0. An
    url format string that is supplied to the regex match's `.template` method
    and then formatted with the remote import path's `rev` and `pkg`. 1. The
    default revision string to use when no `rev` is supplied; ie 'HEAD' or
    'master' for git. 2. An integer indicating the number of leading path
    components to strip from files upacked from the archive.  An example
    configuration that works against <http://github.com|github.com> is:
    {r'<http://github.com/(?P<user>[^/]+)/(?P<repo>[^/]+)|github.com/(?P<user>[^/]+)/(?P<repo>[^/]+)>':
    ('<https://github.com/\g<user>/\g<repo>/archive/{rev}.zip>', 'master', 1)}