Interesting.  The result of making these changes is legal code looking like
>>> if a:
    if b:
        c = 3
This has been proposed as the way Shell should work, but rejected as likely too confusing to beginners as the indented code does not look indented compared to the line above.  The use of tabs for indents in Shell has long been considered a wart that is a 'least bad solution'.

Please hold your proposals.  I intend to solve the issue by moving the prompt to a shell sidebar and use the same indent in shell as in editors.  #37903 has a PR under review.