patch 8.1.1346: error for Python exception does not show useful info

Problem:    Error for Python exception does not show useful info.
Solution:   Show the last line instead of the first one. (Ben Jackson,
            closes #4381)
diff --git a/src/testdir/test_python3.vim b/src/testdir/test_python3.vim
index 514661e..aacc5a5 100644
--- a/src/testdir/test_python3.vim
+++ b/src/testdir/test_python3.vim
@@ -160,3 +160,11 @@
 
   bwipe!
 endfunction
+
+func Test_Catch_Exception_Message()
+  try
+    py3 raise RuntimeError( 'TEST' )
+  catch /.*/
+    call assert_match( '^Vim(.*):RuntimeError: TEST$', v:exception )
+  endtry
+endfunc