Fixed the handling of exceptions that sub-class C++ exceptions

Resolves: bz#2225259

sip6-fix-exception-handling.patch

@@ -0,0 +1,12 @@
+diff --git a/sipbuild/generator/parser/rules.py b/sipbuild/generator/parser/rules.py
+index c221ad7..e79e1b8 100644
+--- a/sipbuild/generator/parser/rules.py
++++ b/sipbuild/generator/parser/rules.py
+@@ -2293,6 +2293,7 @@ def p_opt_base_exception(p):
+ 
+     if len(p) == 4:
+         base = p[2]
++        base.make_absolute()
+ 
+         # See if it is a project-defined exception.
+         for xd in p.parser.pm.spec.exceptions: