diff --git a/bitbake/lib/bb/build.py b/bitbake/lib/bb/build.py
index 04979acbd3..a4deb00b88 100644
--- a/bitbake/lib/bb/build.py
+++ b/bitbake/lib/bb/build.py
@@ -188,6 +188,11 @@ class LogTee(object):
 def exec_func(func, d, dirs = None, pythonexception=False):
     """Execute a BB 'function'"""
 
+    try:
+        oldcwd = os.getcwd()
+    except:
+        oldcwd = None
+
     body = d.getVar(func, False)
     if not body:
         if body is None:
@@ -211,9 +216,7 @@ def exec_func(func, d, dirs = None, pythonexception=False):
             bb.utils.mkdirhier(adir)
         adir = dirs[-1]
     else:
-        adir = d.getVar('B', True)
-        bb.utils.mkdirhier(adir)
-
+        adir = None
     ispython = flags.get('python')
 
     lockflag = flags.get('lockfiles')
@@ -257,6 +260,13 @@ def exec_func(func, d, dirs = None, pythonexception=False):
         else:
             exec_func_shell(func, d, runfile, cwd=adir)
 
+    if oldcwd and os.getcwd() != oldcwd:
+        try:
+            bb.warn("Task %s changed cwd to %s" % (func, os.getcwd()))
+            os.chdir(oldcwd)
+        except:
+            pass
+
 _functionfmt = """
 {function}(d)
 """
@@ -272,7 +282,8 @@ def exec_func_python(func, d, runfile, cwd=None, pythonexception=False):
     if cwd:
         try:
             olddir = os.getcwd()
-        except OSError:
+        except OSError as e:
+            bb.warn("%s: Cannot get cwd: %s" % (func, e))
             olddir = None
         os.chdir(cwd)
 
@@ -298,8 +309,8 @@ def exec_func_python(func, d, runfile, cwd=None, pythonexception=False):
         if cwd and olddir:
             try:
                 os.chdir(olddir)
-            except OSError:
-                pass
+            except OSError as e:
+                bb.warn("%s: Cannot restore cwd %s: %s" % (func, olddir, e))
 
 def shell_trap_code():
     return '''#!/bin/sh\n