Switch /usr/bin/ipa to Python 3

When building RPMs with Python 3 support, /usr/bin/ipa will now
use Python 3.
The in-tree ipa command will also run on Python 3.

When building with make install, $(PYTHON) is honored and it will
still default to Python 2.

Part of the work for https://fedorahosted.org/freeipa/ticket/5638

Reviewed-By: Petr Spacek <pspacek@redhat.com>

freeipa.spec.in

@@ -422,7 +422,11 @@ Summary: IPA administrative tools
 Group: System Environment/Base
 BuildArch: noarch
 Requires: %{name}-client-common = %{version}-%{release}
+%if 0%{?with_python3}
+Requires: python3-ipalib = %{version}-%{release}
+%else
 Requires: python2-ipalib = %{version}-%{release}
+%endif
 Requires: python-ldap
 
 Provides: %{alt_name}-admintools = %{version}
@@ -731,6 +735,13 @@ make client-install DESTDIR=%{buildroot}
 (cd ipapython && make PYTHON=%{__python3} IPA_VERSION_IS_GIT_SNAPSHOT=no %{?_smp_mflags} DESTDIR=%{buildroot} install)
 (cd ipaplatform && %{__python3} setup.py install --root %{buildroot})
 (cd ipaclient && %{__python3} setup.py install --root %{buildroot})
+
+# Switch shebang of /usr/bin/ipa
+# XXX: This script is installed with ipaserver. When all of ipaserver is
+# built with Python 3, this will no longer be necessary (as long as the py3
+# version is installed after the py2 version, so it overwrites /usr/bin/ipa)
+sed -i -e'1s/python\(2\|$\)/python3/' %{buildroot}%{_bindir}/ipa
+
 %endif # with_python3
 
 %find_lang %{gettext_domain}

ipa

@@ -1,4 +1,4 @@
-#!/usr/bin/python2
+#!/usr/bin/python3
 
 # Authors:
 #   Jason Gerard DeRose <jderose@redhat.com>