Add cep for a new history format

[mariusvniekerk]

Additionally we should formalize that a conda environment does not require a history file to exist.

There are several conda command like conda list that require the history file to exist but for much of conda operation this is simply not needed

[chenghlee]

Additionally we should formalize that a conda environment does not require a history file to exist.

If we're going to do that, then we need to also define what makes some directory a conda environment. In the absence of any other standard, I've been using "if foo/conda-meta/history exists, then foo is by definition a conda environment". (Possibly one that's been tampered with, but a conda environment nonetheless.)

[wolfv]

Marius and I were discussing and maybe the existence of a conda-meta folder is enough?