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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<div class='path'>path: <a href='/guix/log/?id=7f2b1c4af0d24f8ce36b1a546d6d853126929551&amp;showmsg=1'>root</a>/<a href='/guix/log/gnu?id=7f2b1c4af0d24f8ce36b1a546d6d853126929551&amp;showmsg=1'>gnu</a>/<a href='/guix/log/gnu/packages?id=7f2b1c4af0d24f8ce36b1a546d6d853126929551&amp;showmsg=1'>packages</a>/<a href='/guix/log/gnu/packages/pcre.scm?id=7f2b1c4af0d24f8ce36b1a546d6d853126929551&amp;showmsg=1'>pcre.scm</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/gnu/packages/pcre.scm?id=7f2b1c4af0d24f8ce36b1a546d6d853126929551'>Collapse</a>)</th><th class='left'>Author</th></tr>
<tr class='logheader'><td><span title='2018-07-22 17:54:54 +0200'>2018-07-22</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/pcre.scm?id=08b87ab0dfa4bae0eb57f3d8915f655bf20d94fc'>gnu: pcre: Update to 8.42.</a></td><td>Marius Bakke</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/pcre.scm (pcre): Update to 8.42.


</td></tr>
<tr class='logheader'><td><span title='2018-07-19 00:53:10 +0200'>2018-07-19</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/pcre.scm?id=50849734e986a5824bcca20fe64b2886f8f1a42b'>gnu: pcre: Install static libraries to separate output.</a></td><td>Marius Bakke</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/pcre.scm (pcre)[outputs]: Add "static".
[arguments]: Add 'move-static-libs' phase.


</td></tr>
<tr class='logheader'><td><span title='2018-02-28 18:23:31 +0100'>2018-02-28</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/pcre.scm?id=8297ff0f931a677c51ca7c64a844a55cd6cd2ef4'>gnu: pcre2: Update to 10.31.</a></td><td>Tobias Geerinckx-Rice</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/pcre.scm (pcre2): Update to 10.31.
[source]: Remove upstreamed patches.
* gnu/packages/patches/pcre2-CVE-2017-7186.patch: Delete this file...
* gnu/packages/patches/pcre2-CVE-2017-8786.patch: ...and this one.
* gnu/local.mk (dist_patch_DATA): Remove them.


</td></tr>
<tr class='logheader'><td><span title='2018-01-19 23:59:20 -0500'>2018-01-19</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/pcre.scm?id=e074a655dd6497daafbd62737e3b63f3d5aa7985'>Merge branch 'master' into core-updates</a></td><td>Mark H Weaver</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
</td></tr>
<tr class='logheader'><td><span title='2018-01-13 21:25:40 +0100'>2018-01-13</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/pcre.scm?id=265c31f5a377851eb583dfeaaaae6132e085cfac'>gnu: pcre: Use HTTPS for home pages.</a></td><td>Tobias Geerinckx-Rice</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/pcre.scm (pcre, pcre2)[home-page]: Use HTTPS.


</td></tr>
<tr class='logheader'><td><span title='2017-10-01 22:16:41 +0300'>2017-10-01</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/pcre.scm?id=0b7f9806dbde1a7c1ded4218e499319d7eafbe7a'>gnu: pcre: Update to 8.41.</a></td><td>Efraim Flashner</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/pcre.scm (pcre): Update to 8.41.
[replacement]: Remove field.
[source]: Remove patch.
(pcre-8.41): Remove variable.
* gnu/patches/pcre-CVE-2017-7186.patch: Remove file.
* gnu/local.mk (dist_patch_DATA): Remove it.


</td></tr>