* gnus.el (gnus-method-to-server): Add an optional parameter so the

* gnus.el (gnus-method-to-server): Add an optional parameter so the
caller can indicate whether the cache should be disregarded for this
call.  This way the result of the call is reproducible at all times and
can be considered a canonical server name for the supplied method.
(gnus-agent-method-p): Canonicalize server names by pushing their
method through `gnus-method-to-server' using the no-cache argument.

* gnus-srvr.el (gnus-server-insert-server-line): Call
`gnus-method-to-server' with `no-cache' argument.

* gnus-agent.el (gnus-agent-toggle-plugged): Don't call
gnus-agent-possibly-synchronize-flags as this should be called when the
server is actually being opened.
(gnus-agent-possibly-synchronize-flags)
(gnus-agent-possibly-synchronize-flags-server): Move check for the
flags file of an agentized server to the latter function.

* gnus-int.el (gnus-agent-possibly-synchronize-flags-server): Autoload.
(gnus-open-server): Call gnus-agent-possibly-synchronize-flags-server
after a connection has been established successfully.