handle Node case
@@ -138,7 +138,7 @@ class Requirements(OrderedDict):
# update dependency
other_ref = other_req.ref
if other_ref and other_ref != req.ref:
- down_reference_str = str(down_ref)
+ down_reference_str = str(down_ref) if down_ref else ""
msg = "requirement %s overridden by %s to %s " \
% (req.ref, down_reference_str or "your conanfile", other_ref)
