pythonPackages.xml2rfc: init at 2.9.8

It seems to work fine, in python2Packages and python3Packages.
If you find a problem, let me know and I'll try to fix it.

(cherry picked from commit 3756efb)

pkgs/development/python-modules/xml2rfc/default.nix

@@ -0,0 +1,23 @@
+{ lib, fetchurl, buildPythonPackage, intervaltree, pyflakes, requests, lxml }:
+
+buildPythonPackage rec {
+  name = "${pname}-${version}";
+  pname = "xml2rfc";
+  version = "2.9.8";
+
+  src = fetchurl {
+    url = "mirror://pypi/x/${pname}/${name}.tar.gz";
+    sha256 = "1img6941wvwpk71q3vi9526bfjbh949k4lphrvdwlcf4igwy435m";
+  };
+
+  propagatedBuildInputs = [ intervaltree pyflakes requests lxml ];
+
+  meta = with lib; {
+    description = "Tool generating IETF RFCs and drafts from XML sources";
+    homepage = https://tools.ietf.org/tools/xml2rfc/trac/;
+    # Well, parts might be considered unfree, if being strict; see:
+    # http://metadata.ftp-master.debian.org/changelogs/non-free/x/xml2rfc/xml2rfc_2.9.6-1_copyright
+    license = licenses.bsd3;
+    maintainers = [ maintainers.vcunat ];
+  };
+}

pkgs/top-level/python-packages.nix

@@ -17253,6 +17253,8 @@ EOF
     };
   });
 
+  xml2rfc = callPackage ../development/python-modules/xml2rfc { };
+
   xmltodict = callPackage ../development/python-modules/xmltodict { };
 
   xarray = callPackage ../development/python-modules/xarray { };