bug#51753: ERC switches to channel buffer on reconnect

[Stefan Kangas]

Severity: important

When ERC reconnects, it switches buffer to the channel buffers.  This is
*very* dangerous.

Consider the situation when the user is about to paste a password and
hit enter with a quick "C-y RET", when all of a sudden the ERC buffer
pops up a fraction of a second before you hit those keys.  Now your
password is on IRC.

At the very least, this behavior should be disabled by default, and
preferably also come with a big warning sign for anyone that intends to
enable it.