Visual mode permanently activates transient-mark-mode

[Óscar Fuentes]

Sorry for reporting this bug here, but BitBucket refuses to work saying
"CSRF verification failed. Request aborted." for whatever I try to do on
it.

I have transient-mark-mode deactivated on my .emacs. Entering Visual
mode activates it (which is fine) but after exiting Visual mode it
remains active (i.e. `transient-mark-mode' var is assigned `t'.)

In Evil's sources I see some complex machinery dealing with
transient-mark-mode, so it is not a case of the devs assuming that all
users have transient-mark-mode on its default setting (active).

To reproduce:

emacs -Q

load and activate Evil.

M-x transient-mark-mode
C-h v transient-mark-mode

Check that the value is nil

v ESC (enter and exit visual mode)

C-h v transient-mark-mode

Now the value is t.