Define %python, but make it work only if %__python is redefined

epel-rpm-macros.spec

@@ -1,6 +1,6 @@
 Name:           epel-rpm-macros
 Version:        8
-Release:        9
+Release:        10
 Summary:        Extra Packages for Enterprise Linux RPM macros
 
 Group:          System Environment/Base
@@ -58,6 +58,9 @@ install -Dpm 644 %{SOURCE3} \
 
 
 %changelog
+* Tue Apr 14 2020 Miro Hrončok <mhroncok@redhat.com> - 8-10
+- Define %%python, but make it work only if %%__python is redefined
+
 * Fri Apr 03 2020 Troy Dawson <tdawson@redhat.com> - 8-9
 - Add %qt5_qtwebengine_arches to macros
 

macros.epel-rpm-macros

@@ -20,6 +20,16 @@
 %python2 %__python2
 %python3 %__python3
 
+# Users can use %%python only if they redefined %%__python (e.g. to %%__python3)
+%python() %{lua:\
+    __python = rpm.expand("%__python")\
+    if __python == "/usr/bin/python" then\
+        rpm.expand("%{error:Cannot use %%python if %%__python wasn't redefined to something other than /usr/bin/python.}")\
+    else\
+        print(__python)\
+    end\
+}
+
 # gpgverify verifies signed sources. There is documentation in the script.
 %gpgverify %{_rpmconfigdir}/gpgverify