principle of uniformity: if a chunk of text has a certain meaning, it will continue to have the same meaning when put into a container block (such as a list item or blockquote).
The following:
List with sublist:
- a
- b
Exact same lines put in a blockquote container block:
>- a
> - b
is rendered by CommonMark 0.29 as

Please compare the above with the example given in the spec just below the definition of the principle of uniformity
A plurality of markdown implementations, including the original Gruber, correctly follow the principle in this regard (I'm counting all the CommonMark implementations as one).
Another example of the issue:
indented 5 spaces
indented 4 spaces
indented 5 spaces
The above lines, in a blockquote:
> indented 5 spaces
> indented 4 spaces
> indented 5 spaces
is rendered as:

Though in this case, all the implementations except MultiMarkdown get it wrong. I would say this latter case is esoteric and unimportant. The first case, the handling of nested lists as demonstrated in the first example, should determine the proper course of action.
The following:
is rendered by CommonMark 0.29 as
Please compare the above with the example given in the spec just below the definition of the principle of uniformity
A plurality of markdown implementations, including the original Gruber, correctly follow the principle in this regard (I'm counting all the CommonMark implementations as one).
Another example of the issue:
is rendered as:
Though in this case, all the implementations except MultiMarkdown get it wrong. I would say this latter case is esoteric and unimportant. The first case, the handling of nested lists as demonstrated in the first example, should determine the proper course of action.