having something synced to the file backend makes numbered files with
So original mtime is lost.
Updating REV is part of converting between remote and local format. It's by design. A "raw file source" would avoid that, see #52791.
*** This bug has been marked as a duplicate of bug 52791 ***
(In reply to comment #1)
> Updating REV is part of converting between remote and local format. It's by
I don't see a good reason for this decision. You lose REV info to store a value that could be stored in X-Whatever property. Ok, that's minor, I think.
> A "raw file source" would avoid that, see #52791.
Sure, when it's ready.
The design decision is that the engine stores a vCard that is not the one that it received. Instead, conceptually, it stores the result of merging local and remote data, which may lead to a different result and thus requires bumping the REV string.
The "cache data in local file" is a special case where no merging happens, but it still follows the same rules in the engine. Changing that requires a different approach.