djbdns/io.py: add a comment about an early return.

diff --git a/djbdns/io.py b/djbdns/io.py
index 7af36a0233949b70039a1e76f1f7042607d66d46..a3e6e430e8a7e7a19890b7d94af36eff3e42b86d 100644 (file)
--- a/djbdns/io.py
+++ b/djbdns/io.py
@@ -42,6 +42,8 @@ def parse_logfile(file : TextIO):
                bufsize=0) as tai:
 
         if not tai.stdin or not tai.stdout:
+            # Mypy tells me that this can happen, based on the type
+            # annotations in the standard library I guess?
             return
 
         for line in file: