Index update fails on Windows

```
What steps will reproduce the problem?
1. cindex any/path
2. cindex
3.

What is the expected output?
The index is updated.

What do you see instead?
After merging the master index with the updated index, the rename of
.csearchindex~~ to .csearchindex fail. This is possibly due to open file
handles.

What version of the product are you using? On what operating system?
Windows 7, 64 bit

Please provide any additional information below.

```

Original issue reported on code.google.com by `fuz...@gmail.com` on 23 Jan 2012 at 10:55