`dbm` errors should contain file names when appropriate, just like `OSError`.
E.g.:
```
>>> open("fooooo")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
FileNotFoundError: [Errno 2] No such file or directory: 'fooooo'
>>> import dbm.gnu
>>> dbm.gnu.open("fooooo")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
_gdbm.error: [Errno 2] No such file or directory
```
the `_gdbm.error` should report the file name `'fooooo'` just like `FileNotFoundError` does (and `exn.args` should contain the file name too!)

I've made a patch which works for me.

>>> dbm.gnu.open("/tmp/zzzzz")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
_gdbm.error: [Errno 2] No such file or directory: '/tmp/zzzzz'
>>> 


Could you please give it a try?

thanks for the patch.
alas, I do not build python myself, so I cannot try it.

Alright, I created a PR for this. We will see if this can be merged to upstream or not.

PR 8590 only changes dbm.gnu. If we do this, we should update dbm.ndbm as well:

    https://github.com/python/cpython/blob/4a745333406a4b9c5b0194bdac4a77d9fadd5457/Modules/_dbmmodule.c#L65

New changeset 9df346bf98069a87de14a3c2f69009d800994c63 by Berker Peksag (Zsolt Cserna) in branch 'master':
bpo-34248: Add filename to error raised in {gnu,ndbm}.open() (GH-8590)
https://github.com/python/cpython/commit/9df346bf98069a87de14a3c2f69009d800994c63