Fixup error message for failed to remove file

Change-Id: I2a9d355ee53b4a70c3ef240ba4e39a4475350a31
Reviewed-on: http://review.couchbase.org/31422
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>