commit fb4e70f9be4b37ab40505118553caf5a5b7c7daf
Author: Bernhard M. Wiedemann <bwiedemann@suse.de>
Date:   Sun Jul 2 11:17:14 2017 +0200

    libutils/man.c: allow to override build time
    
    in order to enable 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.

diff --git a/libutils/man.c b/libutils/man.c
index ef2cd1a28..ba46ba895 100644
--- a/libutils/man.c
+++ b/libutils/man.c
@@ -206,6 +206,11 @@ void ManPageWrite(Writer *out, const char *program, time_t last_modified,
                   const struct option options[],
                   const char *const option_hints[], bool accepts_file_argument)
 {
+    time_t overridetime;
+    char *source_date_epoch = getenv("SOURCE_DATE_EPOCH");
+    if (source_date_epoch != NULL &&
+        (overridetime = (time_t)strtoll(source_date_epoch, NULL, 10)) > 0)
+        last_modified = overridetime;
     WriteCopyright(out);
     WriteHeader(out, program, last_modified);
     WriteName(out, program, short_description);