[repo] optimize massive insertion/deletion by using the new set_operation function Idea is that on massive insertion, cost of handling the list of operation become non negligeable, so we should minimize the number of operations in that list. The set_operation function ease usage of operation associated to data in session.transaction_data, and we only add the operation when data set isn't initialized yet, else we simply add data to the set. The operation then simply process accumulated data.

"""server side objects

:organization: Logilab
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:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
"""