Consider reporting attribute differences when files have not changed

[johnmhoran]

I recently ran DeltaCode on two ScanCode scans of the same codebase (which happened to be e2fsprogs-1.44.2). Both scans were run with ScanCode v2.9.2 -- the difference:

• One scan was run with the latest 2.9.2 release.
• The other scan was run from a post-release branch (new-license-rules) in which several license-detection rules had been changed from those in the 2.9.2 release.

DeltaCode detected 0 deltas -- if a file's sha1 is the same in the two codebases being compared, the file is treated as unmodified; and in this case, the sha1 attribute of each file remained unchanged.

However, there may be use cases where detection of a change in some other attribute(s) -- including a ScanCode-specific attribute like the identification/characterization of a license -- would be valuable to the user, perhaps provided through use of an attribute-specific option/flag.