The global .pdbrc file is determined by the %HOME% environment variable. However, this is not available out of the box on e.g. windows 7 systems. Here only %HOMEDRIVE% and %HOMEPATH% are defined.

Thus the usual approach to have a global .pdbrc file on windows is to define a %HOME% environment variable by hand. This could be avoided if the global .pdbrc would be determined by os.path.expanduser("~/.pdbrc"), which works on current windows and does the magic behind.

There are two possible approaches to improve this situation:
* explicitly mention in the docs that on windows a %HOME% varialbe need to be created manually
* patch pdb.py to use os.path.expanduser instead (see attached diff)

For reference, see also old discussion https://mail.python.org/pipermail/python-list/2005-October/349550.html.

We have a patch to review or we need a doc patch, unless someone has a different idea to the approaches suggested by the originator.  I prefer the idea of changing the code, manually changing environment variables just seems wrong to me, but I won't lose any sleep over it.

expanduser() sounds like the better choice here.

New changeset 7ea9a85f132b32347fcbd2cbe1b553a2e9890b56 by Steve Dower (Timothy Hopper) in branch 'master':
bpo-20523: pdb searches for .pdbrc in ~ instead of $HOME (GH-11847)
https://github.com/python/cpython/commit/7ea9a85f132b32347fcbd2cbe1b553a2e9890b56

New changeset 1ff7dd681c7f3e31524bfada6d6d2786d4e37704 by Miss Islington (bot) in branch '3.7':
bpo-20523: pdb searches for .pdbrc in ~ instead of $HOME (GH-11847)
https://github.com/python/cpython/commit/1ff7dd681c7f3e31524bfada6d6d2786d4e37704

New changeset 79af3bd1d170ed6a72a5c126e862590cdbf192d7 by Miss Islington (bot) in branch '3.8':
bpo-20523: pdb searches for .pdbrc in ~ instead of $HOME (GH-11847)
https://github.com/python/cpython/commit/79af3bd1d170ed6a72a5c126e862590cdbf192d7