BUG #18248: Expression is always zero

The following bug has been logged on the website:

Bug reference:      18248
Logged by:          RekGRpth
Email address:      rekgrpth@gmail.com
PostgreSQL version: 16.1
Operating system:   docker alpine
Description:

The value of expression 'thistimecnt >> 31 >> 31 >> 2' (in
src/timezone/zic.c) is zero regardless of the value of the left operand
'thistimecnt', because it is shifted by 64 (in total) bits, which is greater
or equal to its size of 64 bits. 

Maybe this was what was meant?
thistimecnt >> 31 >> 2