Honor SOURCE_DATE_EPOCH variable to avoid non-determinism in generated
"autoloads" files.

--- a/lisp/emacs-lisp/autoload.el
+++ b/lisp/emacs-lisp/autoload.el
@@ -419,8 +419,12 @@
   ;;              nil t))
   ;;        (match-end 2))))
   (insert generate-autoload-section-header)
-  (prin1 `(autoloads ,autoloads ,load-name ,file ,time)
-	 outbuf)
+  (let* ((env  (getenv "SOURCE_DATE_EPOCH"))
+         (time (if env
+                   (seconds-to-time (string-to-number env))
+                 time)))
+    (prin1 `(autoloads ,autoloads ,load-name ,file ,time)
+           outbuf))
   (terpri outbuf)
   ;; Break that line at spaces, to avoid very long lines.
   ;; Make each sub-line into a comment.
>
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<div class='path'>path: <a href='/guix/log/?id=bd1bce0896150d7351d0c5553d197b0d628d8471'>root</a>/<a href='/guix/log/tests?id=bd1bce0896150d7351d0c5553d197b0d628d8471'>tests</a>/<a href='/guix/log/tests/dsa.key?id=bd1bce0896150d7351d0c5553d197b0d628d8471'>dsa.key</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/dsa.key?id=bd1bce0896150d7351d0c5553d197b0d628d8471&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-05-04 09:56:12 +0200'>2020-05-04</span></td><td><a href='/guix/commit/tests/dsa.key?id=43408e304ffb1149f35cb539b40d673d567c9116'>Add (guix openpgp).</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/openpgp.scm, tests/openpgp.scm, tests/civodul.key,
tests/dsa.key, tests/ed25519.key, tests/rsa.key,
tests/ed25519.sec: New files.
* Makefile.am (MODULES): Add guix/openpgp.scm.
(SCM_TESTS): Add tests/openpgp.scm.
(EXTRA_DIST): Add tests/*.key and tests/ed25519.sec.
</span></span></td><td>Ludovic Courtès</td></tr>