B14016 - monster detection of mimics

When display_monster was changed in 3.4.0 to take multiple sightflags, the
mimic case was not updated completely.

doc/fixes34.1

@@ -320,6 +320,8 @@ second attack for two-weapon combat will miss if first knocks target away
 jousting effect no longer occurs every time riding character hits with lance
 skeletons should be able to wear the armor they're created with
 bouncing zaps should not bounce around the edge of closed doors
+mimics that are detected but not seen should not display as their mimiced
+	form when the detection ends
 
 
 Platform- and/or Interface-Specific Fixes

src/display.c

@@ -371,7 +371,7 @@ display_monster(x, y, mon, sightflags, worm_tail)
      * the mimic was mimicing.
      */
 
-    if (mon_mimic && sightflags) {
+    if (mon_mimic && (sightflags == PHYSICALLY_SEEN)) {
 	switch (mon->m_ap_type) {
 	    default:
 		impossible("display_monster:  bad m_ap_type value [ = %d ]",