[gnome-nibbles] Take into the account the worm's reduction of body when checking for collision with itself

[Iulian Radu <iulianradu src gnome org>]

commit 939a12c3c3ce454eb37117651df2c293a0add926
Author: Iulian Radu <iulian radu67 gmail com>
Date:   Fri Jul 3 16:14:07 2015 +0300

    Take into the account the worm's reduction of body when checking for collision with itself

 src/nibbles-game.vala |    4 ++--
 src/worm.vala         |   12 ++++++++----
 2 files changed, 10 insertions(+), 6 deletions(-)
---
diff --git a/src/nibbles-game.vala b/src/nibbles-game.vala
index 7a61c7b..3282969 100644
--- a/src/nibbles-game.vala
+++ b/src/nibbles-game.vala
@@ -205,9 +205,9 @@ public class NibblesGame : Object
             foreach (var other_worm in worms)
             {
                 if (worm.will_collide_with_head (other_worm)
-                    && worm != other_worm)
+                    && worm != other_worm
+                    && !other_worm.is_stopped)
                     {
-                        stderr.printf("[Debug] Head collision\n");
                         worm.die (walls);
                         other_worm.die (walls);
                         continue;
diff --git a/src/worm.vala b/src/worm.vala
index f88f786..b760437 100644
--- a/src/worm.vala
+++ b/src/worm.vala
@@ -122,8 +122,6 @@ public class Worm : Object
 
         /* Add a new body piece */
         list.offer_head (position);
-        /* Mark the tile as occupied by the worm's body */
-        walls[head ().x, head ().y] = NibblesGame.WORMCHAR + id;
 
         if (remove)
         {
@@ -134,6 +132,9 @@ public class Worm : Object
         else
             added ();
 
+        /* Mark the tile as occupied by the worm's body */
+        walls[head ().x, head ().y] = NibblesGame.WORMCHAR + id;
+
         if (!key_queue.is_empty)
             dequeue_keypress ();
     }
@@ -142,9 +143,12 @@ public class Worm : Object
     {
         var position = position_move ();
 
-        if (walls[position.x, position.y] > NibblesGame.EMPTYCHAR &&
-            walls[position.x, position.y] < 'z' + numworms)
+        if (walls[position.x, position.y] > NibblesGame.EMPTYCHAR
+            && walls[position.x, position.y] < 'z' + numworms
+            && position != list.last ()) /* The last position of the worm won't exist in the next frame */
+        {
             return false;
+        }
 
         return true;
     }