Regression test for Bug #20385
Fixed #20385: Incorrect normalization of userinfo

Net_URL2 internally did unexpectedly change no-userinfo into an empty
userinfo on normalize().

This has been fixed by not normalizing userinfo if there is none in
NetURL2::normalize().
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.