Fix teleporting not unhiding polyed hero

doc/fixes37.0

@@ -91,6 +91,7 @@ praying on an unaligned altar outside of Gehennom behaved like an ordinary
 	prayer; make that always fail
 Discworld typo: Moving Pictures passage 12 "or" -> "of"
 unicorn corpses and wraith corpses could be sacrificed even if "too old"
+hero polymorphed into a hider and hiding was not unhidden when teleporting
 
 
 Fixes to 3.7.0-x Problems that Were Exposed Via git Repository

src/dungeon.c

@@ -1440,6 +1440,7 @@ int x, y;
 #ifdef CLIPPING
     cliparound(u.ux, u.uy);
 #endif
+    u.uundetected = 0;
     /* ridden steed always shares hero's location */
     if (u.usteed)
         u.usteed->mx = u.ux, u.usteed->my = u.uy;