Why PHP does not parse “BRST” dates anymore?

Question

BRST refers to "Brasília Summer Time"

Before version 7.0.26, PHP could parse this string without any problem:

$date = DateTime("Mon Jan 01 20:00:00 BRST 2017");

After that version, PHP returns:

Fatal error: Uncaught Exception: DateTime::__construct(): Failed to 
parse time string (Mon Jan 01 20:00:00 BRST 2017) at position 4 (J): 
The timezone could not be found in the database in /in/c6K56:5
Stack trace:
#0 /in/c6K56(5): DateTime->__construct('Mon Jan 01 20:0...')
#1 {main}
  thrown in /in/c6K56 on line 5

Process exited with code 255.

I searched in changelogs, but I couldn't find any explanation for that.

Here is the example:

https://3v4l.org/c6K56#v7026

Answer 1

You can see in this commit the timezonemap.h file was updated to remove the references to brst along with many other abbreviations.

The commit message reads:

Update timezonemap.h, which needs to match the bundled TZ db

---

Digging deeper (thanks @JamesThorpe) you can see the abbreviations were introduced in July 1999 by Paul Eggert. Notably he claims to have invented these himself:

I invented the English-language abbreviations, and I also invented the other rows to be consistent with the -3:00 row.

This tz commit in December 2016 (again by Eggert) removes the abbreviations and replaces them with the following text:

These tables use numeric abbreviations like -03 and -0330 for integer hour and minute UTC offsets. Although earlier editions used alphabetic time zone abbreviations, these abbreviations were invented and did not reflect common practice.