Trac Ticket #335 - transaction retries need to be cache aware
Commit bddb5a45f2cd27705cb6629f436ef9a7e2248677 includes this fix:
> Additinally, error checking for the conflict value in index_add_mods
> was week (curr_attr). This patch is adding the check.
The fix was incomplete. If an add-attempted attribute type itself
does not exist in the entry (not only the attribute value) after
mods applied, the attribute type/value should not have been indexed.
This patch fixes it.