The perfective verb опереться (to lean on) has the strangest conjugation in the future and imperative, what is the etymological reason for it?

Question

From the impf/pf pair опираться/опереться (=to lean on), опереться seems to be the only verb that exhibits the following strange conjugations, though apparently belonging to the -e- conjugation group:

Future: обопру́сь / обопрёшься / обопру́тся (the prefix об- suddenly appears, with an apparent disappearance of the first mobile e in all forms?)

Past: опёрся / оперла́сь / опёрлись (no final л in the first person singular?)

Imperative: обопри́сь / обопрёмся / обопри́тесь (again, with the prefix об-?).

Could someone share the etymological or historical reason for such strange conjugations, in particular the appearance in the future and imperfective of the prefix об- and its meaning?

Answer 1

That topic is still controversial among academicians and other scientists.

There exist three similar prefixes in Russian: о-, об-, обо-. It's difficult to give a rule for these, and the only information of I know of is in Efremova's dictionary.

Native Russian speakers such as I usually differentiate the usage of these on a casual basis and what sounds best to the ear.