Applied first review notes from Robert-André Mauchin

Ref.:

    https://bugzilla.redhat.com/show_bug.cgi?id=1595420#c1

ydiff.spec.in

@@ -6,10 +6,11 @@ URL:        https://github.com/ymattw/ydiff
 License:    BSD
 Source0:    __APP_URLBASE__/archive/%{version}/%{name}-%{version}.tar.gz
 BuildRequires: python2-devel
+BuildRequires: python3-devel
 BuildArch: noarch
 
 Requires: less
-Requires: python2-%{name}
+Requires: python%{python3_pkgversion}-%{name}
 %description
 Term based tool to view colored, incremental diff in a Git/Mercurial/Svn
 workspace or from stdin, with side by side (similar to diff -y) and auto
@@ -20,15 +21,23 @@ Summary: %{summary}
 %description -n python2-%{name}
 Python library that implements API used by ydiff tool.
 
+%package -n     python3-%{name}
+Summary:        %{summary}
+%{?python_provide:%python_provide python3-%{name}}
+%description -n python3-%{name}
+Python library that implements API used by ydiff tool.
+
 %prep
 %autosetup -n %{name}-%{version}
 /usr/bin/sed -i '/#!\/usr\/bin\/env python/d' ydiff.py
 
 %build
 %py2_build
+%py3_build
 
 %install
 %py2_install
+%py3_install
 
 %files
 %doc README.rst
@@ -41,6 +50,11 @@ Python library that implements API used by ydiff tool.
 %{python2_sitelib}/%{name}.pyo
 %{python2_sitelib}/%{name}-*.egg-info
 
+%files -n python3-%{name}
+%{python3_sitelib}/__pycache__/*
+%{python3_sitelib}/%{name}.py
+%{python3_sitelib}/%{name}-%{version}-py?.?.egg-info
+
 %changelog
 * __APP_DATE__ Alois Mahdal <netvor+ydiff@vornet.cz> - __APP_VERSION__-__APP_RELEASE__
 - Unofficial experimental RPM pseudo-release