fixup! fixup! Add tests and implementation for ZoneInfo

Author: pganssle

Lib/zoneinfo/_common.py

@@ -105,11 +105,7 @@ def get_abbr(idx):
         assert c == b"\n", c
 
         tz_bytes = b""
-        # TODO: Walrus operator
-        while True:
-            c = fobj.read(1)
-            if c == b"\n":
-                break
+        while (c := fobj.read(1)) != b"\n":
             tz_bytes += c
 
         tz_str = tz_bytes