set +o posix disables allowing tab as input

[Linda Walsh]

I have my tab key set to generate a tab key instead of doing auto complete
and use ` for auto complete -- not ideal, but it works.

I found a bug in this today.

GNU bash, version 4.2.45(1)-release (x86_64-suse-linux-gnu)

if I type in "set +o posix"

to make sure posix mode is 'off',
then 'tab' is no longer allowed as input.

Ideas?