Comment 3 for bug 523566

3 1/2 years later ... still affecting Raring.

$ sudo dpkg -i ../simple-scan_3.8.0-0ubuntu2~tj_amd64.deb
[sudo] password for tj:
dpkg-split: error: unable to read part file `../simple-scan_3.8.0-0ubuntu2~tj_amd64.deb': Permission denied
dpkg: error processing ../simple-scan_3.8.0-0ubuntu2~tj_amd64.deb (--install):
 subprocess dpkg-split returned error exit status 2
Errors were encountered while processing:
 ../simple-scan_3.8.0-0ubuntu2~tj_amd64.deb

$ ls -l ../simple-scan_3.8.0-0ubuntu2~tj_amd64.deb
-rw------- 1 tj tj 242276 Jul 17 17:13 ../simple-scan_3.8.0-0ubuntu2~tj_amd64.deb

$ umask
0002
$ touch ../test-umask.tmp
$ ls -l ../test-umask.tmp
-rw-rw-r-- 1 tj tj 0 Jul 17 17:20 ../test-umask.tmp