gnu: python: Make the build reproducible.

While Python build was reproducible on a single machine, once multiple file
systems entered the picture, it was no longer true.  The solution adopted by
the upstream (and Debian) was cherry-picked.

More info: <https://github.com/python/cpython/pull/8226>.

* gnu/packages/python.scm (python-3.10) [source]: Apply reproducibility patch.

Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Modified-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Change-Id: I0273dc0f8511a7acdcc2b462a26cc29a9756c801

gnu/local.mk

@@ -1970,6 +1970,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/python-3-hurd-configure.patch		\
   %D%/packages/patches/python-angr-addition-type-error.patch	\
   %D%/packages/patches/python-angr-check-exec-deps.patch	\
+  %D%/packages/patches/python-3-reproducible-build.patch	\
   %D%/packages/patches/python-aionotify-0.2.0-py3.8.patch	\
   %D%/packages/patches/python-argcomplete-1.11.1-fish31.patch	\
   %D%/packages/patches/python-cross-compile.patch		\

gnu/packages/patches/python-3-reproducible-build.patch

@@ -0,0 +1,30 @@
+From 6c8ea7c1dacd42f3ba00440231ec0e6b1a38300d Mon Sep 17 00:00:00 2001
+From: Inada Naoki <songofacandy@gmail.com>
+Date: Sat, 14 Jul 2018 00:46:11 +0900
+Subject: [PATCH] Use FLAG_REF always for interned strings
+
+---
+ Python/marshal.c | 9 +++++++--
+ 1 file changed, 7 insertions(+), 2 deletions(-)
+
+diff --git a/Python/marshal.c b/Python/marshal.c
+index 6d06266c6a8e2e..51db2e3b2e29a2 100644
+--- a/Python/marshal.c
++++ b/Python/marshal.c
+@@ -275,9 +275,14 @@ w_ref(PyObject *v, char *flag, WFILE *p)
+     if (p->version < 3 || p->hashtable == NULL)
+         return 0; /* not writing object references */
+ 
+-    /* if it has only one reference, it definitely isn't shared */
+-    if (Py_REFCNT(v) == 1)
++    /* If it has only one reference, it definitely isn't shared.
++     * But we use TYPE_REF always for interned string, to PYC file stable
++     * as possible.
++     */
++    if (Py_REFCNT(v) == 1 &&
++            !(PyUnicode_CheckExact(v) && PyUnicode_CHECK_INTERNED(v))) {
+         return 0;
++    }
+ 
+     entry = _Py_HASHTABLE_GET_ENTRY(p->hashtable, v);
+     if (entry != NULL) {

gnu/packages/python.scm

@@ -435,6 +435,7 @@ (define-public python-3.10
                         "python-3-deterministic-build-info.patch"
                         "python-3-fix-tests.patch"
                         "python-3-hurd-configure.patch"
+                        "python-3-reproducible-build.patch"
                         "python-3-search-paths.patch"))
               (sha256
                (base32