tests: use egrep with regular expression branches for compatibility
GNU grep allows you to use "a\|b" in a regular expression to match either
"a" or "b", but at least Solaris grep does not; only egrep allows for that.
And egrep considers "a+" to be "a{1,}" instead of an "a" and a literal plus
sign, so escape that as well.
http://example.com/no/anchor, branches: (None, [])
http://example.com/an/anchor, branches: ('foo', [])
http://example.com/no/anchor/branches, branches: (None, ['foo'])
http://example.com/an/anchor/branches, branches: ('bar', ['foo'])
http://example.com/an/anchor/branches-None, branches: ('foo', [])
http://example.com/, branches: (None, [])
http://example.com/, branches: (None, [])
http://example.com/, branches: ('foo', [])