s-s-d: Preserve faulting errno when printing reason in fatal function

debian/changelog

@@ -90,6 +90,8 @@ dpkg (1.15.1) UNRELEASED; urgency=low
     Ubuntu vendor class to inherit from it.
   * Do not set the Arch substvar in dpkg-source, avoiding generating warnings
     when there's no compiler present. Closes: #526132
+  * Preserve faulting errno when printing reason in start-stop-daemon fatal
+    function.
 
   [ Frank Lichtenheld ]
   * Dpkg::Version: Remove unnecessary function next_elem which just

utils/start-stop-daemon.c

@@ -223,12 +223,13 @@ static void
 fatal(const char *format, ...)
 {
 	va_list arglist;
+	int errno_fatal = errno;
 
 	fprintf(stderr, "%s: ", progname);
 	va_start(arglist, format);
 	vfprintf(stderr, format, arglist);
 	va_end(arglist);
-	fprintf(stderr, " (%s)\n", strerror (errno));
+	fprintf(stderr, " (%s)\n", strerror(errno_fatal));
 	exit(2);
 }