Give informative error message when the to-be-downloaded file cannot be created
 

> >
> > Unfortunately, the "failed to create file" error message is printed for
> > every mirror (that can be dozens of lines), which is ugly, but at least
> > informative... Without modifying the download logic (for example, by
> > introducing -2 return value for _alpm_download() to indicate giving up),
> > this ugliness cannot be eliminated.
> I'm all for modifying the download logic in this fashion.

OK. But not today :-). Then some other cases can also get retval -2, so
we can eliminate some other pointless retries for every mirrors.

> Not a huge fan of the phrasing of this message. In most cases, I'd
> rather the filename or variable part of the message be at the front or
> the end, not in the middle. Perhaps
> _("could not open file '%s': %s
"), tempfile_name, strerror(errno))

OK, done in my working branch:
http://repo.or.cz/w/pacman-ng.git/shortlog/refs/heads/working

NG