Renaming a file on Debian Wheezy does not work using fs.rename or fs.renameSync.
This only happens in files moved from /tmp/ to another location.
The reported error is: EXDEV, cross-device link not permitted.
Debian Wheezy uses tmpfs for the /tmp folder by default.
This can be turned off by modifing /etc/default/rcS.
RAMTMP=yes
has to be set to
RAMTMP=no