^P vs sanity_check

Normally when sanity_check is enabled it will take place for every
command executed.  Avoid that when the command is ^P because if a
sanity warning is a recurring one and the msg_window setting is
single or combination (tty-only) which shows one message, ^P will
just repeat each new warning without having any chance to cycle back
to earlier messages.

doc/fixes3-7-0.txt

@@ -1187,6 +1187,9 @@ don't exclude map column 1 from consideration when rloc() picks a random spot
 	for destination of a teleported monster
 covetous monster attacking another monster to acquire special item would not
 	do so if positioned diagonally adjacent
+skip sanity_check handling when current command is ^P, otherwise it might
+	re-trigger and show new sanity warning every time when set for
+	line-at-a-line feedback
 
 
 Fixes to 3.7.0-x General Problems Exposed Via git Repository

src/cmd.c

@@ -188,11 +188,14 @@ static const char *readchar_queue = "";
 static const char unavailcmd[] = "Unavailable command '%s'.";
 /* for rejecting #if !SHELL, !SUSPEND */
 static const char cmdnotavail[] = "'%s' command not available.";
+/* doesn't need to be in struct g|gw */
+static boolean was_doprev = FALSE;
 
 /* the #prevmsg command */
 static int
 doprev_message(void)
 {
+    was_doprev = TRUE;
     (void) nh_doprev_message();
     return ECMD_OK;
 }
@@ -4265,6 +4268,14 @@ you_sanity_check(void)
 void
 sanity_check(void)
 {
+    if (was_doprev) {
+        /* in case a recurring sanity_check warning occurs, we mustn't
+           re-trigger it when ^P is used, otherwise msg_window:Single
+           and msg_window:Combination will always repeat the most recent
+           instance, never able to go back to any earlier messages */
+        was_doprev = FALSE;
+        return;
+    }
     you_sanity_check();
     obj_sanity_check();
     timer_sanity_check();