Seems more likely the columns are wrong.
I don't know of any standard where the week begins on Saturday. It's correct
for Monday based calendars.
Package: bsdmainutils
Version: 9.0.7
Severity: grave
Justification: renders package unusable
-----BEGIN screenshot-----
tglase@tglase:~ $ cal
März 2016
Sa So Mo Di Mi Do Fr
1 2 3 4 5 6
7 8 9 10 1̲1̲ 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30 31
tglase@tglase:~ $ LC_ALL=C cal
March 2016
Sa Su Mo Tu We Th Fr
1 2 3 4 5 6
7 8 9 10 1̲1̲ 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30 31
tglase@tglase:~ $ date
Fre Mär 11 15:49:33 CET 2016
tglase@tglase:~ $ LC_ALL=C date
Fri Mar 11 15:49:38 CET 2016
tglase@tglase:~ $ schroot -c sid-amd64
(sid-amd64)tglase@tglase:~ $ LC_ALL=C cal
March 2016
Sa Su Mo Tu We Th Fr
1 2 3 4 5 6
7 8 9 10 1̲1̲ 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30 31
-----END screenshot-----
Of course, feel free to downgrade the severity, but this
occurs on x32 and amd64 both and offers wrong data to the
user.