[GSoC] [RFC] stashing unmerged index entries

Reference: https://git.github.io/SoC-2019-Ideas/#teach-git-stash-to-handle-unmerged-index-entries

"When the index is unmerged, git stash refuses to do anything. That is unnecessary, though, as it could easily craft e.g. an octopus merge of the various stages. A subsequent git stash apply can detect that octopus and re-generate the unmerged index."

according to it we take the unmerged entries (caused by conflicted merge) in index from all stages, and do an octopus merge. how does this solve the problem, i mean where do those entries go after octopus merge ? a conflicted merge is still there, do we store the merge separately ?