gnu: serf: Build with Python 3.

* gnu/packages/patches/serf-python3.patch: New file.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.
* gnu/packages/web.scm (serf)[source](patches): New field.
[arguments]: Remove #:scons.

gnu/local.mk

@@ -1609,6 +1609,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/sdl-libx11-1.6.patch			\
   %D%/packages/patches/seed-webkit.patch			\
   %D%/packages/patches/seq24-rename-mutex.patch			\
+  %D%/packages/patches/serf-python3.patch			\
   %D%/packages/patches/sharutils-CVE-2018-1000097.patch		\
   %D%/packages/patches/shadow-hurd-pctrl.patch			\
   %D%/packages/patches/shishi-fix-libgcrypt-detection.patch	\

gnu/packages/patches/serf-python3.patch

@@ -0,0 +1,29 @@
+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'])

gnu/packages/web.scm

@@ -1792,6 +1792,7 @@ from streaming URLs.  It is a command-line wrapper for the libquvi library.")
        (method url-fetch)
        (uri (string-append "mirror://apache/serf/serf-"
                            version ".tar.bz2"))
+       (patches (search-patches "serf-python3.patch"))
        (sha256
         (base32 "1k47gbgpp52049andr28y28nbwh9m36bbb0g8p0aka3pqlhjv72l"))))
     (build-system scons-build-system)
@@ -1804,8 +1805,7 @@ from streaming URLs.  It is a command-line wrapper for the libquvi library.")
        ;;("gss" ,gss)
        ("zlib" ,zlib)))
     (arguments
-     `(#:scons ,scons-python2
-       #:scons-flags (list (string-append "APR=" (assoc-ref %build-inputs "apr"))
+     `(#:scons-flags (list (string-append "APR=" (assoc-ref %build-inputs "apr"))
                            (string-append "APU=" (assoc-ref %build-inputs "apr-util"))
                            (string-append "OPENSSL=" (assoc-ref %build-inputs "openssl"))
                            ;; (string-append "GSSAPI=" (assoc-ref %build-inputs "gss"))