Hi,

I found that if a session's working directory is renamed or moved, `pwd` doesn't show the real working directory.

Example:

Session 1:

```

~/ $ mkdir test

~/ $ cd test

~/test $ touch file

```

Session 2:

```

~/ $ mv test test_2

~/ $ mkdir test

~/ $ cd test

~/ $ touch file2

~/ $ ls

file2

~/ $

```

Session 1 (still running during session 2):

```

~/test $ ls

file

~/test $ pwd

/Users/<user>/test

~/test $ realpath file

/Users/<user>/test_2/file

~/test $ realpath nonExistenFile

/Users/<user>/test_2/nonExistenFile

```

It seems that `realpath` does show the updated path, but `pwd` doesn't

Tested on MacOS (10.14.3) and Ubuntu 16.04 / 18.04

Thanks,

Chris