Collection::Bag provides a default if there is no default specified in
the attribute... This breaks if we want to use either lazy_build or
builder, e.g.:
Setting both default and builder is not allowed. at
/usr/lib64/perl5/vendor_perl/5.10.0/x86_64-linux-thread-multi/Class/MOP/Attribute.pm
line 43
You can not use lazy_build and default for the same attribute
(_dependson) at
/usr/lib/perl5/vendor_perl/5.10.0/Moose/Meta/Attribute.pm line 328
Changing the test at lib/MooseX/AttributeHelpers/Collection/Bag.pm line
30 to check for lazy_build, default and builder should do the trick :)