Improve error on failed quit

The error message in PtyReplSessions Drop impl implies that the
subprocess is "bash", which isn't necessarily true and might confuse
users.
So we print the process name instead

Co-authored-by: Matthias Beyer <mail@beyermatthias.de>
Signed-off-by: phaer <hello@phaer.org>

Author: phaer

src/session.rs

@@ -342,7 +342,7 @@ impl Drop for PtyReplSession {
         if let Some(ref cmd) = self.quit_command {
             self.pty_session
                 .send_line(cmd)
-                .expect("could not run `exit` on bash process");
+                .expect(&format!("could not run `{}` on child process", cmd));
         }
     }
 }