fixup! Regression test for Bug #20385

@covers notation was missing
Regression test for Bug #20399
Fixed #20399: Setting userinfo to FALSE not transparent

Setting userinfo to FALSE in Net_URL2::setUserinfo() was not consistent
with getting it later on via Net_URL2::getUserinfo() as it was silently
converted to a zero-length string.

This has been fixed by not converting FALSE to string.