Update Portage to sync BlockerDB at init, rather than before every package.

pym/_emerge/BlockerDB.py

Index: pym/_emerge/BlockerDB.py
diff --git a/pym/_emerge/BlockerDB.py b/pym/_emerge/BlockerDB.py
index fd4bf5ecebe149821c301234904b2971461dfc8d..f5adc4d6728999854dda44ea99787d45b2627bd6 100644
--- a/pym/_emerge/BlockerDB.py
+++ b/pym/_emerge/BlockerDB.py
@@ -30,12 +30,7 @@ class BlockerDB(object):
 				"vartree"     :  fake_vartree,
 		}}
 
-	def _get_fake_vartree(self, acquire_lock=0):
-		fake_vartree = self._fake_vartree
-		fake_vartree.sync(acquire_lock=acquire_lock)
-		return fake_vartree
-
-	def findInstalledBlockers(self, new_pkg, acquire_lock=0):
+	def findInstalledBlockers(self, new_pkg):
 		"""
 		Search for installed run-time blockers in the root where
 		new_pkg is planned to be installed. This ignores build-time
@@ -45,7 +40,7 @@ class BlockerDB(object):
 		dep_keys = ["RDEPEND", "PDEPEND"]
 		settings = self._vartree.settings
 		stale_cache = set(blocker_cache)
-		fake_vartree = self._get_fake_vartree(acquire_lock=acquire_lock)
+		fake_vartree = self._fake_vartree
 		dep_check_trees = self._dep_check_trees
 		vardb = fake_vartree.dbapi
 		installed_pkgs = list(vardb)
@@ -118,3 +113,7 @@ class BlockerDB(object):
 
 		return blocking_pkgs
 
+	def discardBlocker(self, pkg):
+		"""Discard a package from the list of potential blockers."""
+		self._fake_vartree.cpv_discard(pkg)
+