fixed double switch on On and Off for iron pipes, now react only on "On"

ironpipe.patch

 .../src/buildcraft/transport/PipeLogicIron.java    |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/buildcraft/common/net/minecraft/src/buildcraft/transport/PipeLogicIron.java b/buildcraft/common/net/minecraft/src/buildcraft/transport/PipeLogicIron.java
index 6a2d8da..d654489 100755
--- a/buildcraft/common/net/minecraft/src/buildcraft/transport/PipeLogicIron.java
+++ b/buildcraft/common/net/minecraft/src/buildcraft/transport/PipeLogicIron.java
@@ -26,7 +26,9 @@ public class PipeLogicIron extends PipeLogic {
 				yCoord, zCoord);
 		
 		if (currentPower != lastPower) {
-			switchPosition();
+			// only switch once
+			if(currentPower)
+				switchPosition();
 			
 			lastPower = currentPower;
 		}