Found while investigating #2296
The problem is that we should not remove a directory locally if it contains
modified files.
But the modification time of the directory is not necessarily chaning (so
the instruction of the directory may still be NONE)
We have to move the child_modified test a bit down to be recursive
We fetch the id from the server, but don't save them in the database.
I Could have used INSTRUCTION_UPDATED for that, but then i would need to update the
reconcile algorithm to take in account the fact that UPDATED is possible there.
Instead, use should_update_etag which means the db is going to be written again
Remove reference to old instruction _UPDATED and _DELETED which does not make sens with
the new propagator
Improve the test to test this case, and that etags are properly writen to the DB
when there is a fake conflict
