From alpine https://gitlab.alpinelinux.org/alpine/aports/-/raw/3.24-stable/testing/zvbi/fix-strptime-input.patch
Skip leading whitespaces to ensure reproducible test results with musl.
--- a/examples/pdc2.c
+++ b/examples/pdc2.c
@@ -1166,6 +1166,9 @@ parse_test_file_line		(time_t *		timestamp,
 	if (!isspace (*s))
 		goto invalid;
 
+	while (isspace (*s))
+		++s;
+
 	memset (&tm, 0, sizeof (tm));
 	tm.tm_isdst = -1; /* unknown */