This used to work but I'm not exaclty sure how long ago; 4.2.x, 4.3.x and 5.0.1 all have the problem.
1. Create a page that includes a non-wiki word % INCLUDE{"non_wiki_word"} % (w/out spaces)
2. Now try to rename the non_wiki_word topic either scanning all public web or limiting search to the current web
2.1 If scan all public webs option is selected no referring links are found
2.2 If limiting search to the current web is selected referring links are skipped
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TWiki:Main/DarrenKinley - 2011-01-15