Remove BuildRequires on python2-sphinx

See https://fedoraproject.org/wiki/Changes/Sphinx2

python-netaddr.spec

@@ -4,7 +4,7 @@
 
 Name:           python-netaddr
 Version:        0.7.19
-Release:        14%{?dist}
+Release:        15%{?dist}
 Summary:        A pure Python network address representation and manipulation library
 
 License:        BSD
@@ -14,7 +14,9 @@ Source0:        https://pypi.python.org/packages/source/n/netaddr/netaddr-%{vers
 BuildArch:      noarch
 BuildRequires:  python2-devel
 BuildRequires:  python2-setuptools
-BuildRequires:  python2-sphinx
+# sphinx is python3-only f31 onward
+# https://fedoraproject.org/wiki/Changes/Sphinx2
+BuildRequires:  python3-sphinx
 BuildRequires:  python2-pytest
 
 Patch0: 0001-fixed-broken-tests-in-issue-149-python-3-regression-.patch
@@ -96,7 +98,7 @@ chmod 0644 README.md AUTHORS CHANGELOG COPYRIGHT LICENSE PKG-INFO
 
 #docs
 pushd docs
-PYTHONPATH='../' sphinx-build -b html -d build/doctrees source html
+PYTHONPATH='../' sphinx-build-%{python3_version} -b html -d build/doctrees source html
 %if 0%{?with_python3}
 PYTHONPATH='../' sphinx-build-%{python3_version} -b html -d build/doctrees source python3/html
 %endif
@@ -135,6 +137,10 @@ py.test-%{python3_version}
 %endif
 
 %changelog
+* Mon Mar 11 2019 John Eckersberg <eck@redhat.com> - 0.7.19-15
+- Remove BuildRequires on python2-sphinx
+  See https://fedoraproject.org/wiki/Changes/Sphinx2
+
 * Sat Feb 02 2019 Fedora Release Engineering <releng@fedoraproject.org> - 0.7.19-14
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_30_Mass_Rebuild