diff -r e6cd37d4dad8 Lib/shutil.py
--- a/Lib/shutil.py	Fri Jan 18 00:10:37 2013 -0500
+++ b/Lib/shutil.py	Fri Jan 18 11:18:45 2013 +0000
@@ -1078,8 +1078,11 @@
 
     # Short circuit. If we're given a full path which matches the mode
     # and it exists, we're done here.
-    if _access_check(cmd, mode):
-        return cmd
+    if os.path.dirname(cmd):
+        if _access_check(cmd, mode):
+            return cmd
+        # Subdirectories are not accessible from PATH directories
+        return None
 
     path = (path or os.environ.get("PATH", os.defpath)).split(os.pathsep)
 
diff -r e6cd37d4dad8 Lib/test/test_shutil.py
--- a/Lib/test/test_shutil.py	Fri Jan 18 00:10:37 2013 -0500
+++ b/Lib/test/test_shutil.py	Fri Jan 18 11:18:45 2013 +0000
@@ -1316,6 +1316,33 @@
             self.assertEqual(rv, os.path.join(tail_dir, self.file))
         finally:
             os.chdir(old_cwd)
+    
+    def test_cwd(self):
+        old_cwd = os.getcwd()
+        base_dir = os.path.dirname(self.dir)
+        os.chdir(self.dir)
+        try:
+            rv = shutil.which(self.file, path=base_dir)
+            if sys.platform == "win32":
+                # Windows: current directory implicitly on PATH
+                self.assertEqual(rv, os.path.join(os.curdir, self.file))
+            else:
+                # Other platforms: shouldn't match in the current directory.
+                self.assertIsNone(rv)
+        finally:
+            os.chdir(old_cwd)
+    
+    def test_cwd_subdir(self):
+        # From the current directory, we can run foo/bar.exe
+        old_cwd = os.getcwd()
+        base_dir, tail_dir = os.path.split(self.dir)
+        os.chdir(base_dir)
+        try:
+            relpath = os.path.join(tail_dir, self.file)
+            rv = shutil.which(relpath, path=self.dir)
+            self.assertEqual(rv, relpath)
+        finally:
+            os.chdir(old_cwd)
 
     def test_nonexistent_file(self):
         # Return None when no matching executable file is found on the path.