Tested on Vim 2.8-2298 - works as expected


E325: ATTENTION
Found a swap file by the name "os_unix.h_swp"
              dated: Tue Jan 05 15:30:39 2021
          [cannot be opened]
While opening file "os_unix.h"
              dated: Mon Jan 04 10:01:44 2021

(1) Another program may be editing the same file.  If this is the case,
     be careful not to end up with two different instances of the same
     file when making changes.  Quit, or continue with caution.
(2) An edit session for this file crashed.
     If this is the case, use ":recover" or "vim -r os_unix.h"
     to recover the changes (see ":help recovery").
     If you did this already, delete the swap file "os_unix.h_swp"
     to avoid this message.

Swap file "os_unix.h_swp" already exists!
"os_unix.h" 500L, 11908B
Press ENTER or type command to continue

On the E325 screen (Found a swap file...), the user can choose 
different keys to press (e.g. [O]pen Read-Only, (E)dit anyway,...). If 
<Esc> is pressed, vim freezes and the terminal session has to be killed.

Reproduce as follows:
1) in one terminal, $ vim a.txt
2) in another terminal, $ vim a.txt
3) vim prompts, warning that there already is a swap file
4) press <Esc> - vim freezes

The same happens in other prompts, e.g. when using ctags, do ":tj 
<identifier>" on an ambiguous tag (i.e. an identifier that is defined 
in multiple places, like :tj main), so vim shows you all the places 
where the tag is defined. You are prompted to choose which one to 
open. Press <Esc> - vim freezes.