Fix build with Python 3 scons.

Patch taken from Arch Linux:
https://github.com/archlinux/svntogit-packages/blob/packages/serf/trunk/scons-python3.patch

--- serf-1.3.9/SConstruct.orig	2019-07-26 17:49:30.910189251 +0000
+++ serf-1.3.9/SConstruct	2019-07-26 17:49:54.073821735 +0000
@@ -163,9 +163,9 @@
               suffix='.def', src_suffix='.h')
   })
 
-match = re.search('SERF_MAJOR_VERSION ([0-9]+).*'
-                  'SERF_MINOR_VERSION ([0-9]+).*'
-                  'SERF_PATCH_VERSION ([0-9]+)',
+match = re.search(b'SERF_MAJOR_VERSION ([0-9]+).*'
+                  b'SERF_MINOR_VERSION ([0-9]+).*'
+                  b'SERF_PATCH_VERSION ([0-9]+)',
                   env.File('serf.h').get_contents(),
                   re.DOTALL)
 MAJOR, MINOR, PATCH = [int(x) for x in match.groups()]
@@ -183,7 +183,7 @@
 
 unknown = opts.UnknownVariables()
 if unknown:
-  print 'Warning: Used unknown variables:', ', '.join(unknown.keys())
+  print ('Warning: Used unknown variables:', ', '.join(unknown.keys()))
 
 apr = str(env['APR'])
 apu = str(env['APU'])
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<tr><td><span title='2020-05-13 09:30:26 +0300'>2020-05-13</span></td><td><a href='/guix/commit/gnu/packages/guile-wm.scm?id=3c986a7dc268756c097212de958f046b29b76c1b'>mailmap: Update entries for Nikita.</a><span class='msg-avail'>...<span class='msg-tooltip'>* .mailmap: change email and name for Nikita.
* Makefile.am, doc/guix.texi, etc/completion/fish/guix.fish,
gnu/packages/accessibility.scm, gnu/packages/admin.scm,
gnu/packages/audio.scm, gnu/packages/autotools.scm, gnu/packages/cdrom.scm,
gnu/packages/check.scm, gnu/packages/cinnamon.scm,
gnu/packages/compression.scm, gnu/packages/crypto.scm,
gnu/packages/databases.scm, gnu/packages/django.scm, gnu/packages/dns.scm,
gnu/packages/elixir.scm, gnu/packages/emacs-xyz.scm, gnu/packages/emacs.scm,
gnu/packages/enlightenment.scm, gnu/packages/erlang.scm,
gnu/packages/fonts.scm, gnu/packages/fontutils.scm, gnu/packages/forth.scm,
gnu/packages/fvwm.scm, gnu/packages/games.scm, gnu/packages/gl.scm,
gnu/packages/gnome.scm, gnu/packages/gnunet.scm, gnu/packages/gnupg.scm,
gnu/packages/gtk.scm, gnu/packages/guile-wm.scm, gnu/packages/guile-xyz.scm,
gnu/packages/haskell-apps.scm, gnu/packages/haskell-check.scm,
gnu/packages/haskell-crypto.scm, gnu/packages/haskell-xyz.scm,
gnu/packages/haskell.scm, gnu/packages/image-viewers.scm,
gnu/packages/image.scm, gnu/packages/irc.scm, gnu/packages/language.scm,
gnu/packages/libcanberra.scm, gnu/packages/linux.scm,
gnu/packages/lisp-xyz.scm, gnu/packages/lisp.scm, gnu/packages/lolcode.scm,
gnu/packages/lxde.scm, gnu/packages/lxqt.scm, gnu/packages/mail.scm,
gnu/packages/markup.scm, gnu/packages/mate.scm, gnu/packages/maths.scm,
gnu/packages/mc.scm, gnu/packages/messaging.scm, gnu/packages/music.scm,
gnu/packages/ncurses.scm, gnu/packages/networking.scm,
gnu/packages/nickle.scm, gnu/packages/openbox.scm, gnu/packages/pdf.scm,
gnu/packages/perl-check.scm, gnu/packages/perl.scm,
gnu/packages/python-compression.scm, gnu/packages/python-crypto.scm,
gnu/packages/python-web.scm, gnu/packages/python-xyz.scm,
gnu/packages/python.scm, gnu/packages/qt.scm, gnu/packages/ruby.scm,
gnu/packages/rust.scm, gnu/packages/scheme.scm,
gnu/packages/serialization.scm, gnu/packages/shells.scm,
gnu/packages/ssh.scm, gnu/packages/suckless.scm, gnu/packages/tbb.scm,
gnu/packages/telephony.scm, gnu/packages/text-editors.scm,
gnu/packages/textutils.scm, gnu/packages/time.scm, gnu/packages/tls.scm,
gnu/packages/tor.scm, gnu/packages/version-control.scm,
gnu/packages/video.scm, gnu/packages/vim.scm, gnu/packages/web.scm,
gnu/packages/wm.scm, gnu/packages/xdisorg.scm, gnu/packages/xfce.scm,
gnu/packages/xml.scm, gnu/packages/xorg.scm, gnu/services/certbot.scm,
gnu/services/desktop.scm, gnu/services/version-control.scm,
gnu/services/web.scm, guix/import/hackage.scm, guix/licenses.scm: Likewise.

Signed-off-by: Efraim Flashner &lt;efraim@flashner.co.il&gt;
</span></span></td><td>nikita</td></tr>