Merge packages asynchronously in Portage.

pym/_emerge/MergeListItem.py

Index: pym/_emerge/MergeListItem.py
diff --git a/pym/_emerge/MergeListItem.py b/pym/_emerge/MergeListItem.py
index e7856ccfc1e5f3afbc57663852eacd4eb217dd9b..64f5a86ef306a19f8c2fecb54d3f2e9aa3252e93 100644
--- a/pym/_emerge/MergeListItem.py
+++ b/pym/_emerge/MergeListItem.py
@@ -111,7 +111,7 @@ class MergeListItem(CompositeTask):
 		self._install_task.wait()
 		return self.returncode
 
-	def merge(self):
+	def merge(self, exit_handler):
 
 		pkg = self.pkg
 		build_opts = self.build_opts
@@ -135,15 +135,14 @@ class MergeListItem(CompositeTask):
 					world_atom=world_atom)
 
 				uninstall.start()
-				retval = uninstall.wait()
-				if retval != os.EX_OK:
-					return retval
-			return os.EX_OK
-
-		if build_opts.fetchonly or \
+				self.returncode = uninstall.wait()
+			else:
+				self.returncode = os.EX_OK
+			exit_handler(self)
+		elif build_opts.fetchonly or \
 			build_opts.buildpkgonly:
-			return self.returncode
-
-		retval = self._install_task.install()
-		return retval
+			exit_handler(self)
+		else:
+			self._current_task = self._install_task
+			self._install_task.install(exit_handler)