Please describe the problem:
The issue is similar to bug 549595 but the patch in that bug does not help.  What's happening is that link() is returning ENOTSUP when used on a drive shared via a wireless router.  The code is only checking for EOPNOTSUPP.  The two error codes are always equal on Linux, but they're different on Mac if compiling in the "follow Unix standards" mode, which apparently MacPorts does when compiling gnucash.

Steps to reproduce:
1. Set up an Airport Extreme base station sharing out an HFS+ disk
2. Put the Gnucash data file on this disk
3. Start Gnucash
4. When prompted about being unable to acquire the lock, tell it to go ahead
   anyway.
5. Try to save the file.


Actual results:
If the patch from bug 549595 is not applied, the file is silently deleted.  If it is, an error alert pops up saying that the file could not be backed up, and after that's dismissed a dialog appears prompting for a different place to save.

Expected results:
I would expect my data to be saved.

Does this happen every time?
Yes.

Other information: