SPEC: filter out /usr/bin/python* requirements

The Python dependencies are already tracked by the python2 or python3
"Requires".  This filters out the python binaries from the RPM
automatic requires/provides scanner.

Before this change, a query for the requirements of the Python 2 package
would reveal:

    $ rpm -qRp fedora-26-noarch/python2-avocado-60.0-1.fc26.noarch.rpm
    /usr/bin/python2
    /usr/bin/python3
    ...

Reference: https://fedoraproject.org/wiki/Packaging:AutoProvidesAndRequiresFiltering#Filtering_provides_and_requires_after_scanningSigned-off-by: NCleber Rosa <crosa@redhat.com>

python-avocado.spec

@@ -32,6 +32,11 @@
 %global with_python3 1
 %endif
 
+# The Python dependencies are already tracked by the python2
+# or python3 "Requires".  This filters out the python binaries
+# from the RPM automatic requires/provides scanner.
+%global __requires_exclude ^/usr/bin/python[23]$
+
 Summary: Framework with tools and libraries for Automated Testing
 Name: python-%{srcname}
 Version: 60.0
@@ -756,6 +761,7 @@ Again Shell code (and possibly other similar shells).
 * Wed Apr  4 2018 Cleber Rosa <cleber@redhat.com> - 60.0-2
 - Moved all requirements to python2-avocado and python3-avocado
 - Added python_provides macro on Python 3 package
+- Filter out python binaries from requirements
 
 * Wed Mar 28 2018 Cleber Rosa <cleber@redhat.com> - 60.0-1
 - Moved "common" dep into python2-avocado and python3-avocado