diff -r 089146b8ccc6 Lib/http/server.py
--- a/Lib/http/server.py	Fri Sep 25 00:49:44 2015 -0400
+++ b/Lib/http/server.py	Fri Sep 25 23:10:53 2015 +0800
@@ -844,6 +844,12 @@
     Raises: IndexError if too many '..' occur within the path.
 
     """
+    # Query component should not be involved.
+    i = path.find('?')
+    if i >= 0:
+        path, query = path[:i], path[i+1:]
+    path = urllib.parse.unquote(path)
+
     # Similar to os.path.split(os.path.normpath(path)) but specific to URL
     # path semantics rather than local operating system semantics.
     path_parts = path.split('/')
@@ -864,6 +870,9 @@
     else:
         tail_part = ''
 
+    if i >= 0:
+        tail_part = '?'.join((tail_part, query))
+
     splitpath = ('/' + '/'.join(head_parts), tail_part)
     collapsed_path = "/".join(splitpath)
 
@@ -947,7 +956,7 @@
         (and the next character is a '/' or the end of the string).
 
         """
-        collapsed_path = _url_collapse_path(urllib.parse.unquote(self.path))
+        collapsed_path = _url_collapse_path(self.path)
         dir_sep = collapsed_path.find('/', 1)
         head, tail = collapsed_path[:dir_sep], collapsed_path[dir_sep+1:]
         if head in self.cgi_directories: