bug#20484: 25.0.50; Directory tracking in ansi-term broken.

[Stefan Monnier]

> It was applied to the "devel" branch soon after:
> http://git.savannah.gnu.org/cgit/bash.git/diff/shell.c?h=devel&id=0385211bb5cb01e0259c64ec2c5cc6337d4e215c

> So, the point has been made, but it will take a long time for this to
> get into the default bash on all the systems Emacs supports.

Good.  So we can revert beaab89896 before 25.1.
We should still keep it a bit longer, in case some other project has
failed to notice the obsolescence of $EMACS.


        Stefan