Versions:
Minecraft 1.5.1
Forge 674
Buildcraft: BuildCraft-1.5.1-jenkins-Buildcraft-126.126

Handled:
2013-04-26 21:15:24 [SEVERE] [APUnofficial] Failed to load default localization.
java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Unknown Source)
at java.util.Properties.load0(Unknown Source)
at java.util.Properties.load(Unknown Source)
at buildcraft.additionalpipes.AdditionalPipes.preInit(AdditionalPipes.java:195)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at cpw.mods.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:494)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:314)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
at com.google.common.eventbus.EventBus.post(EventBus.java:267)
at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:165)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:314)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
at com.google.common.eventbus.EventBus.post(EventBus.java:267)
at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:98)
at cpw.mods.fml.common.Loader.loadMods(Loader.java:514)
at cpw.mods.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:85)
at cpw.mods.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:350)
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:69)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:429)
at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:573)

Unhandled/server crash:
2013-04-26 21:15:29 [SEVERE] [Minecraft-Server] Encountered an unexpected exception LoaderException
cpw.mods.fml.common.LoaderException: java.lang.NoSuchMethodError: buildcraft.transport.Pipe.getIconProvider()Lbuildcraft/api/core/IIconProvider;
at cpw.mods.fml.common.LoadController.transition(LoadController.java:142)
at cpw.mods.fml.common.Loader.initializeMods(Loader.java:691)
at cpw.mods.fml.server.FMLServerHandler.finishServerLoading(FMLServerHandler.java:93)
at cpw.mods.fml.common.FMLCommonHandler.onServerStarted(FMLCommonHandler.java:355)
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:140)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:429)
at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:573)
Caused by: java.lang.NoSuchMethodError: buildcraft.transport.Pipe.getIconProvider()Lbuildcraft/api/core/IIconProvider;
at buildcraft.additionalpipes.AdditionalPipes.createPipeSpecial(AdditionalPipes.java:447)
at buildcraft.additionalpipes.AdditionalPipes.loadPipes(AdditionalPipes.java:334)
at buildcraft.additionalpipes.AdditionalPipes.init(AdditionalPipes.java:215)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at cpw.mods.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:494)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:314)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
at com.google.common.eventbus.EventBus.post(EventBus.java:267)
at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:165)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:314)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
at com.google.common.eventbus.EventBus.post(EventBus.java:267)
at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:98)
at cpw.mods.fml.common.Loader.initializeMods(Loader.java:690)

Should be fixed.