commit fb7b152478b28d998c781f1ad924675b85c314db
Author: Bernhard M. Wiedemann <bwiedemann@suse.de>
Date:   Sat Jul 8 15:32:36 2017 +0200

    Allow to override build date
    
    in order to allow for reproducible builds.
    See https://reproducible-builds.org/ for why this is good
    and https://reproducible-builds.org/specs/source-date-epoch/
    for the definition of this variable.
    
    Also use gmtime instead of localtime to be independent of timezone.

diff --git a/lib/doc/bin/kernel-doc b/lib/doc/bin/kernel-doc
index 0c8bf6a..2851162 100755
--- a/lib/doc/bin/kernel-doc
+++ b/lib/doc/bin/kernel-doc
@@ -253,10 +253,11 @@ my %highlights = %highlights_man;
 my $blankline = $blankline_man;
 my $modulename = "Kernel API";
 my $function_only = 0;
+my $build_date = $ENV{SOURCE_DATE_EPOCH} || time;
 my $man_date = ('January', 'February', 'March', 'April', 'May', 'June',
 		'July', 'August', 'September', 'October',
-		'November', 'December')[(localtime)[4]] .
-  " " . ((localtime)[5]+1900);
+		'November', 'December')[(gmtime($build_date))[4]] .
+  " " . ((gmtime($build_date))[5]+1900);
 my $show_not_found = 0;
 
 # Essentially these are globals.