Original implementation is using time.daylight to detect if DST is active and that's not correct since the time.daylight returns:

Nonzero if a DST timezone is defined.

The time.daylight tells us if current timezone uses DST, thus not if the DST is currently active. This leads to condition where time.daylight is always 1 and never changes since my timezone always uses DST but of course the DST is active only sometimes.

That's why we need to detect if the DST is currently active instead.

The time.localtime().tm_isdst returns:

In calls to mktime(), tm_isdst may be set to 1 when daylight savings time is in effect, and 0 when it is not. A value of -1 indicates that this is not known, and will usually result in the correct state being filled in.

This should fix the DST detection.