wrap tempfile.mkstemp to work on windows

The path returned by tempfile.mkstemp is encoded in system locale,
since we need to pass it through rpc, we need it to be encoded in UTF-8

views/file.py

@@ -7,7 +7,6 @@ view_trash_file, view_snapshot_file
 import os
 import simplejson as json
 import stat
-import tempfile
 import urllib
 import urllib2
 import chardet
@@ -38,7 +37,7 @@ from seahub.wiki.models import WikiDoesNotExist, WikiPageMissing
 from seahub.utils import get_httpserver_root, show_delete_days, render_error, \
     get_file_type_and_ext, gen_file_get_url, gen_shared_link, is_file_starred, \
     get_file_contributors, get_ccnetapplet_root, render_permission_error, \
-    is_textual_file, show_delete_days
+    is_textual_file, show_delete_days, mkstemp
 from seahub.utils.file_types import (IMAGE, PDF, IMAGE, DOCUMENT, MARKDOWN, \
                                          TEXT, SF)
 from seahub.settings import FILE_ENCODING_LIST, FILE_PREVIEW_MAX_SIZE, \
@@ -570,7 +569,7 @@ def file_edit_submit(request, repo_id):
     content = content.encode(encoding)
 
     # first dump the file content to a tmp file, then update the file
-    fd, tmpfile = tempfile.mkstemp()
+    fd, tmpfile = mkstemp()
     def remove_tmp_file():
         try:
             os.remove(tmpfile)