#172 Clock scan -1 month produces wrong year

[Anonymous]

OriginalBugID: 5071 Bug
Version: 8.3
SubmitDate: '2000-04-13'
LastModified: '2000-04-13'
Severity: SER
Status: Closed
Submitter: shawn
ChangedBy: redman
RelatedBugIDs: 5070
OS: Windows NT
FixedDate: '2000-10-25'
ClosedDate: '2000-04-13'

Clock goes back 13 months instead of 1

Reproducible steps:
#A Date in Jan 2001
% set prev_month 979444800
979444800
% clock format 979444800
Sat Jan 13 20:00:00 Pacific Standard Time 2001
# Scan back a month
% set prev_month [clock scan {-1 month} -base [clock scan $date ]]
can't read "date": no such variable
% set date "Sat Jan 13 2001"
Sat Jan 13 2001
% set prev_month [clock scan {-1 month} -base [clock scan $date ]]
945144060
# Expect Dec 2000
% clock format $prev_month
Mon Dec 13 20:01:00 Pacific Standard Time 1999
%