clear pits in temporary corridor

From a bug report, then leave the corridor (causing it to
> vanish), the pit will be embedded in rock instead of being removed.

clear any pits that the hero digs in the vault guard's temporary corridor

doc/fixes34.4

@@ -202,6 +202,7 @@ Magicbane should not produce "<something> are confused" message
 handle antholes more sensibly when ants aren't available
 cancelled nurses shouldn't say "Relax, this won't hurt a bit"
 check for hero location in digactualhole() before clearing u.utrap
+clear any pits that the hero digs in the vault guard's temporary corridor
 
 
 Platform- and/or Interface-Specific Fixes

src/vault.c

@@ -46,6 +46,7 @@ boolean forceshow;
 	struct monst *mtmp;
 	boolean sawcorridor = FALSE;
 	struct egd *egrd = EGD(grd);
+	struct trap *trap = (struct trap *)0;
 
 	if (!on_level(&egrd->gdlevel, &u.uz)) return TRUE;
 
@@ -68,6 +69,13 @@ boolean forceshow;
 			    (void) rloc(mtmp, FALSE);
 			}
 		}
+		if ((trap = t_at(fcx,fcy)) != 0 &&
+		     trap->ttyp == PIT && trap->madeby_u &&
+		     IS_STWALL(egrd->fakecorr[fcbeg].ftyp)) {
+		     /* you dug a pit while following the guard out,
+			so fill it in when the location reverts to stone */
+			deltrap(trap);
+		}
 		if (levl[fcx][fcy].typ == CORR && cansee(fcx, fcy))
 		    sawcorridor = TRUE;
 		levl[fcx][fcy].typ = egrd->fakecorr[fcbeg].ftyp;