Home path is missing the drive letter on Windows

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What steps will reproduce the problem?
1. cindex any/path (without CSEARCHINDEX set)
2.
3.

What is the expected output?
Using .csearchindex in home dir.

What do you see instead?
Failing due to the home path missing the drive letter. In index/read.go, the
line in File() getting the home dir should probably read 'home =
os.Getenv("HOMEDRIVE") + os.Getenv("HOMEPATH")'

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 10:39