set global logging levels from project settings if not already explicitly set

main/src/main/scala/sbt/LogManager.scala

@@ -66,6 +66,25 @@ object LogManager
 		case _ => key // should never get here
 	}
 
+	// if global logging levels are not explicitly set, set them from project settings
+	private[sbt] def setGlobalLogLevels(s: State, data: Settings[Scope]): State =
+		if(hasExplicitGlobalLogLevels(s))
+			s
+		else {
+			val logging = s.globalLogging
+			def get[T](key: SettingKey[T]) = key in GlobalScope get data
+			def transfer(l: AbstractLogger, traceKey: SettingKey[Int], levelKey: SettingKey[Level.Value]) {
+				get(traceKey).foreach(l.setTrace)
+				get(levelKey).foreach(l.setLevel)
+			}
+			logging.full match {
+				case a: AbstractLogger => transfer(a, traceLevel, logLevel)
+				case _ => ()
+			}
+			transfer(logging.backed, persistTraceLevel, persistLogLevel)
+			s
+		}
+
 	private[this] def setExplicitGlobalLogLevels(s: State, flag: Boolean): State =
 		s.put(BasicKeys.explicitGlobalLogLevels, flag)
 	private[this] def hasExplicitGlobalLogLevels(s: State): Boolean =

main/src/main/scala/sbt/Project.scala

@@ -223,8 +223,9 @@ object Project extends ProjectExtra
 		val (onLoad, onUnload) = getHooks(structure.data)
 		val newAttrs = unloaded.attributes.put(stateBuildStructure, structure).put(sessionSettings, session).put(Keys.onUnload.key, onUnload)
 		val newState = unloaded.copy(attributes = newAttrs)
-		onLoad(updateCurrent( newState ))
+		onLoad(LogManager.setGlobalLogLevels(updateCurrent( newState ), structure.data))
 	}
+
 	def orIdentity[T](opt: Option[T => T]): T => T = opt getOrElse idFun
 	def getHook[T](key: SettingKey[T => T], data: Settings[Scope]): T => T  =  orIdentity(key in GlobalScope get data)
 	def getHooks(data: Settings[Scope]): (State => State, State => State)  =  (getHook(Keys.onLoad, data), getHook(Keys.onUnload, data))