Currently it treats it as an invalid thumbnail URL:
Nov 15 06:51:39 ms-fe1001 proxy-server: HTTP status code mismatch. Mediawiki: 200 Thumbor: 400 URL: http://upload.wikimedia.org/wikipedia/commons/thumb/c/c1/NRCSGA02066_-_Georgia_%282035%29%28NRCS_Photo_Gallery%29.tif/lossless-page1-731px-NRCSGA02066_-_Georgia_%282035%29%28NRCS_Photo_Gallery%29.tif.png Nov 15 07:14:00 ms-fe1001 proxy-server: HTTP status code mismatch. Mediawiki: 200 Thumbor: 400 URL: http://upload.wikimedia.org/wikipedia/commons/thumb/c/ca/Tower_Heist_marching_band_jeh.theora.ogv/mid-Tower_Heist_marching_band_jeh.theora.ogv.jpg Nov 15 07:20:46 ms-fe1001 proxy-server: HTTP status code mismatch. Mediawiki: 200 Thumbor: 400 URL: http://upload.wikimedia.org/wikipedia/commons/thumb/4/4f/Cajon_summit,_c._1919.tiff/lossless-page1-375px-Cajon_summit,_c._1919.tiff.png Nov 15 07:36:47 ms-fe1001 proxy-server: HTTP status code mismatch. Mediawiki: 200 Thumbor: 400 URL: http://upload.wikimedia.org/wikipedia/de/thumb/9/96/J%C3%B6rg_L%C3%BCcke.tif/lossless-page1-97px-J%C3%B6rg_L%C3%BCcke.tif.png Nov 15 09:02:40 ms-fe1001 proxy-server: HTTP status code mismatch. Mediawiki: 200 Thumbor: 400 URL: http://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/NRCSCO01098_-_Colorado_%281575%29%28NRCS_Photo_Gallery%29.tif/lossless-page1-171px-NRCSCO01098_-_Colorado_%281575%29%28NRCS_Photo_Gallery%29.tif.png Nov 15 09:14:54 ms-fe1001 proxy-server: HTTP status code mismatch. Mediawiki: 200 Thumbor: 400 URL: http://upload.wikimedia.org/wikipedia/commons/thumb/3/36/Kanu_Sitzposition.tif/lossless-page1-1024px-Kanu_Sitzposition.tif.png Nov 15 09:14:56 ms-fe1001 proxy-server: HTTP status code mismatch. Mediawiki: 200 Thumbor: 400 URL: http://upload.wikimedia.org/wikipedia/commons/thumb/0/01/Kajak_Sitzposition.tif/lossless-page1-1024px-Kajak_Sitzposition.tif.png Nov 15 10:04:42 ms-fe1001 proxy-server: HTTP status code mismatch. Mediawiki: 200 Thumbor: 400 URL: http://upload.wikimedia.org/wikipedia/commons/thumb/6/66/New_York_US_Congressional_District_1_%28since_2013%29.tif/lossless-page1-141px-New_York_US_Congressional_District_1_%28since_2013%29.tif.png Nov 15 10:23:27 ms-fe1001 proxy-server: HTTP status code mismatch. Mediawiki: 200 Thumbor: 400 URL: http://upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Ritratto_di_Paolo_Magretti.TIF/lossless-page1-41px-Ritratto_di_Paolo_Magretti.TIF.png Nov 15 11:02:08 ms-fe1001 proxy-server: HTTP status code mismatch. Mediawiki: 200 Thumbor: 400 URL: http://upload.wikimedia.org/wikipedia/commons/thumb/2/21/EvaPerryMoore.tif/lossless-page1-65px-EvaPerryMoore.tif.png