Fix player teleportation bug whilst sneaking

Only set back position when sneaking if player wasn't teleported by adding and using a bool "got_teleported" to player
it fixes #2876

src/localplayer.cpp

@@ -183,7 +183,7 @@ void LocalPlayer::move(f32 dtime, Environment *env, f32 pos_max_d,
 	*/
 	if (control.sneak && m_sneak_node_exists &&
 			!(fly_allowed && g_settings->getBool("free_move")) && !in_liquid &&
-			physics_override_sneak) {
+			physics_override_sneak && !got_teleported) {
 		f32 maxd = 0.5 * BS + sneak_max;
 		v3f lwn_f = intToFloat(m_sneak_node, BS);
 		position.X = rangelim(position.X, lwn_f.X-maxd, lwn_f.X+maxd);
@@ -204,6 +204,9 @@ void LocalPlayer::move(f32 dtime, Environment *env, f32 pos_max_d,
 		}
 	}
 
+	if (got_teleported)
+		got_teleported = false;
+
 	// this shouldn't be hardcoded but transmitted from server
 	float player_stepheight = touching_ground ? (BS*0.6) : (BS*0.2);
 

src/network/clientpackethandler.cpp

@@ -552,6 +552,7 @@ void Client::handleCommand_MovePlayer(NetworkPacket* pkt)
 
 	*pkt >> pos >> pitch >> yaw;
 
+	player->got_teleported = true;
 	player->setPosition(pos);
 
 	infostream << "Client got TOCLIENT_MOVE_PLAYER"

src/player.cpp

@@ -33,6 +33,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 
 Player::Player(IGameDef *gamedef, const char *name):
+	got_teleported(false),
 	touching_ground(false),
 	in_liquid(false),
 	in_liquid_stable(false),

src/player.h

@@ -318,6 +318,7 @@ public:
 	// Use a function, if isDead can be defined by other conditions
 	bool isDead() { return hp == 0; }
 
+	bool got_teleported;
 	bool touching_ground;
 	// This oscillates so that the player jumps a bit above the surface
 	bool in_liquid;