[meld] build_helpers: Work around pre-release micro release string

[Kai Willadsen <kaiw src gnome org>]

commit f449d20334aa301df301195e15e6e96d106d01de
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Fri Jul 5 11:38:11 2019 +1000

    build_helpers: Work around pre-release micro release string
    
    Current Fedora rawhide apparently has `4rc2` as its micro release
    string, which is clearly just great.

 meld/build_helpers.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meld/build_helpers.py b/meld/build_helpers.py
index f9fb302b..1772aa01 100644
--- a/meld/build_helpers.py
+++ b/meld/build_helpers.py
@@ -34,7 +34,7 @@ from distutils.log import info
 try:
     import distro
 except ImportError:
-    python_version = tuple(int(x) for x in platform.python_version_tuple())
+    python_version = tuple(int(x) for x in platform.python_version_tuple()[:2])
     if python_version >= (3, 8):
         print(
             'Missing build requirement "distro" Python module; '