Honor the 'SOURCE_DATE_EPOCH' environment variable to allow for
determinitic builds.

--- a/Lib/py_compile.py
+++ b/Lib/py_compile.py
@@ -105,7 +105,10 @@ def compile(file, cfile=None, dfile=None, doraise=False):
     """
     with open(file, 'U') as f:
         try:
-            timestamp = long(os.fstat(f.fileno()).st_mtime)
+            if 'SOURCE_DATE_EPOCH' in os.environ:
+                timestamp = long(os.environ['SOURCE_DATE_EPOCH'])
+            else:
+                timestamp = long(os.fstat(f.fileno()).st_mtime)
         except AttributeError:
             timestamp = long(os.stat(file).st_mtime)
         codestring = f.read()
diff --git a/Python/import.c b/Python/import.c
index e47ce63..7eecf9c 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -945,6 +945,11 @@ write_compiled_module(PyCodeObject *co, char *cpathname, struct stat *srcstat, t
     /* Now write the true mtime (as a 32-bit field) */
     fseek(fp, 4L, 0);
     assert(mtime <= 0xFFFFFFFF);
+    if (Py_GETENV("SOURCE_DATE_EPOCH") != NULL) {
+	const char *epoch = Py_GETENV("SOURCE_DATE_EPOCH");
+	mtime = atoi(epoch);
+    }
+
     PyMarshal_WriteLongToFile((long)mtime, fp, Py_MARSHAL_VERSION);
     fflush(fp);
     fclose(fp);
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<tr><td><span title='2019-04-28 22:57:07 +0200'>2019-04-28</span></td><td><a href='/guix/commit/gnu/installer/final.scm?id=0e8e963d73e61c7666f9ec4efa98c1a277c72af9'>installer: User accounts can now have a "real name."</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/newt/user.scm (run-user-add-page): Add #:real-name.  Add
a label and entry for the real name and initialize the 'real-name' field
of the &lt;user&gt; record.
* gnu/installer/final.scm (create-user-database): Set the 'comment'
field of the &lt;user-account&gt; record.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-04-26 14:19:36 +0200'>2019-04-26</span></td><td><a href='/guix/commit/gnu/installer/final.scm?id=9529f7850e3ae91cce70620e684fc6d0dc25e815'>installer: Take 'guix system init' exit code into account.</a><span class='msg-avail'>...<span class='msg-tooltip'>This allows the installer to distinguish success from failure, and also
ensures the shell that runs 'guix system init' exits upon completion.

* gnu/installer/utils.scm (run-shell-command)[pause]: New procedure.
Add "exec" before COMMAND in the script.  Guard 'invoke' call and handle
'invoke-error?'.  Add call to 'pause' on completion.
* gnu/installer/final.scm (install-system): Remove 'false-if-exception'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-04-25 00:45:35 +0200'>2019-04-25</span></td><td><a href='/guix/commit/gnu/installer/final.scm?id=91a7c4998fe4f5a2a63f2ddb4bfeeef81c68b6d7'>installer: Ask for the root account password.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://bugs.gnu.org/35399&gt;.

* gnu/installer/newt/user.scm (run-root-password-page): New procedure.
* gnu/installer/user.scm (users-&gt;configuration): Filter out the "root"
account.
* gnu/installer/final.scm (create-user-database): Set 'uid' field in
'user-account' form.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-04-25 00:45:34 +0200'>2019-04-25</span></td><td><a href='/guix/commit/gnu/installer/final.scm?id=898677ed17672130d20434cd88575d620c97c553'>installer: Ask for user password and initialize /etc/shadow.</a><span class='msg-avail'>...<span class='msg-tooltip'>Partly fixes &lt;https://bugs.gnu.org/35399&gt;.

* gnu/installer/user.scm (&lt;user&gt;)[password]: New field.
* gnu/installer/final.scm (%seed): New variable.
(integer-&gt;alphanumeric-char, random-string)
(create-user-database): New procedures.
(install-system): Call 'create-user-database'.
* gnu/installer/newt/final.scm (run-install-shell): Add #:users and pass
it to 'install-system'.
(run-final-page): Pass #:users to 'run-install-shell'.
* gnu/installer/newt/user.scm (run-user-add-page): Add password entry.
Pass its result as the 'password' field of &lt;user&gt;.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-04-23 00:34:47 +0200'>2019-04-23</span></td><td><a href='/guix/commit/gnu/installer/final.scm?id=7611074f677f1c3cfe5da426f387eeda1b6ad825'>installer: Run 'guix system init' with the right locale.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/utils.scm (run-shell-command): Add #:locale and honor it.
* gnu/installer/newt/final.scm (run-install-shell): Add 'locale'
parameter; pass it to 'install-system'.
(run-final-page): Obtain locale from RESULT; pass it to 'run-install-shell'.
* gnu/installer/final.scm (install-system): Add 'locale' parameter; pass
it to 'run-shell-command'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-01-17 14:04:22 +0100'>2019-01-17</span></td><td><a href='/guix/commit/gnu/installer/final.scm?id=dc5f3275ecbddc804875899e9e457299a835d7ab'>installer: Add configuration formatter.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer.scm (installer-steps): Add configuration-formatter procedures.
* gnu/installer/final.scm: New file.
* gnu/installer/locale.scm (locale-&gt;configuration): New exported procedure.
* gnu/installer/newt.scm (newt-installer): Add final page.
* gnu/installer/newt/final.scm: New file.
* gnu/installer/record.scm (installer): Add final-page field.
* gnu/installer/timezone.scm (posix-tz-&gt;configuration): New exported
procedure.
* gnu/installer/steps.scm (installer-step): Rename configuration-proc field to
configuration-formatter.
(%installer-configuration-file): New exported parameter,
(%installer-target-dir): ditto,
(%configuration-file-width): ditto,
(format-configuration): new exported procedure,
(configuration-&gt;file): new exported procedure.
</span></span></td><td>Mathieu Othacehe</td></tr>