Outlining is incorrect with nested namespaces when a child namespace matches a parent namespace

[sean-mcmanus]

Repro is

namespace foo1
{
	int foo1;
	namespace foo2
	{
		namespace foo1::foo4
		{
			int foo2;
		}
		int foo1;
	}
}

Changing foo1::foo4 to foo3::foo4 shows the correct behavior.

Not sure if any real world code would be hitting this, but it could point to an underlying problem with the algorithm used that could potentially be causing other bugs.