Now, we don't have user option to make completions with case insensitive.
It would be nice if user have option to enable/disable case insensitive completions.

Python is a case-sensitive language. Why would case-insensitive completions be useful?

This is a new feature, so it would have to go into 3.9, all older versions are in feature-freeze.

Yes. Python is case sensitive language and this feature will not break its essence.
This case insensitive completion will help interpreter user for easy typing and choose from the available options.
In the following example even user typed 'os.po', completions will give user all the options ignoring case:

>>>  os.po
os.POSIX_FADV_DONTNEED    os.POSIX_FADV_NORMAL      os.POSIX_FADV_SEQUENTIAL  os.popen(                 os.posix_fallocate(       
os.POSIX_FADV_NOREUSE     os.POSIX_FADV_RANDOM      os.POSIX_FADV_WILLNEED    os.posix_fadvise(         
>>> os.po

And finally, this is implemented as an controllable user option with default value as 'case sensitive'. So user can choose to go case insensitive or not. Even core 'readline' also provide this option with 'set completion-ignore-case on'.

Thanks for the suggestion and for the high quality PR, Madhusudhan!

I'm not sure about this feature. It seems harmless enough, with the default being the existing case-sensitive completion. But it seems like a rather esoteric thing to want, so I'm not sure it's worth adding to the stdlib and maintaining indefinitely.

Would you mind bringing this up for discussion on Python-Ideas, so that we can get a feel for how many others would find this useful?

Thanks for your suggestion Tal Einat.
I have created an discussion topic @ https://discuss.python.org/t/autocompletion-with-case-insensitive-option/6017

Please do support.

It seems like this would be a very good feature to have for accesibility, because persons with low level disabilities (e.g. carpal syndrom) will generally have a harder time keeping shift down while pressing a few upper case letters, and they would often have caps lock remapped to Esc or Ctrl to make them more easily usable since caps lock is almost never used. I don't have disability but that's what I've heard!

This should probably be brought up in the python-ideas mailing list, which is much more active than the group on discuss.python.org.