Index: Lib/shutil.py
===================================================================
--- Lib/shutil.py	(revision 60672)
+++ Lib/shutil.py	(working copy)
@@ -210,4 +210,10 @@
             os.unlink(src)
 
 def destinsrc(src, dst):
-    return abspath(dst).startswith(abspath(src))
+    src = abspath(src)
+    dst = abspath(dst)
+    if not src.endswith(os.path.sep):
+        src += os.path.sep
+    if not dst.endswith(os.path.sep):
+        dst += os.path.sep
+    return dst.startswith(src)
Index: Lib/test/test_shutil.py
===================================================================
--- Lib/test/test_shutil.py	(revision 60672)
+++ Lib/test/test_shutil.py	(working copy)
@@ -161,7 +161,29 @@
             finally:
                 shutil.rmtree(TESTFN, ignore_errors=True)
 
+    def test_destinsrc_1(self):
+        os.mkdir(TESTFN)
+        try:
+            for src, dst in [('srcdir', 'srcdir/dest')]:
+                src = os.path.join(TESTFN, src)
+                dst = os.path.join(TESTFN, dst)
+                self.assert_(shutil.destinsrc(src, dst),
+                             msg='destinsrc() wrongly concluded that '
+                             'dst (%s) is not in src (%s)' % (dst, src))
+        finally:
+            shutil.rmtree(TESTFN, ignore_errors=True)
 
+    def test_destinsrc_2(self):
+        os.mkdir(TESTFN)
+        try:
+            for src, dst in [('srcdir', 'src/dest'), ('srcdir', 'srcdir.new')]:
+                src = os.path.join(TESTFN, src)
+                dst = os.path.join(TESTFN, dst)
+                self.failIf(shutil.destinsrc(src, dst),
+                            msg='destinsrc() wrongly concluded that '
+                            'dst (%s) is in src (%s)' % (dst, src))
+        finally:
+            shutil.rmtree(TESTFN, ignore_errors=True)
 
 def test_main():
     test_support.run_unittest(TestShutil)