This reverts commit 4e105385d046e2aeab16955943df97c5eefa3a6f, reversing
changes made to 62b43839098bbbbfc4be789128d33dc0612f1ab3.
The change in Ruby that made those changes required was reverted in
8852fa8760
Regexp#match? should be considered to be part of the Ruby core library. We are
emulating it for < 2.4, but not having to require the extension is part of the
illusion of the emulation.
In Ruby ^ and $ mean start and end of *line*.
A regexp that validates an email should not check if
some line of the string looks like an email, and maybe
be surrounded by the entire Joyce's Ulysses. What the
regexp has to check is if the string itself looks like
an email.
This validator is used only in tests, the ^/$ anchors
implied no risk.
