Page Comparison

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1. Attempt to replace a file that does not exist in the collection.
   1. The user should be informed that the operation failed because the file did't exist.

Unreachable file replace

1. Attempt to replace a file in the collection, providing the correct checksums, but a wrong url (the url validates, but no file is found).
   
   1. The user should be informed that the pillars were unable to locate the file at the given url.

Replace with returned checksums

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