This commit has the following benefits:

- Remove `sh` as a development dependency.
- Increase test coverage on Windows.
- Improve the robustness of some tests against leftover `.env` files in
  the repository.
    - This is not perfect yet: If you have a `.env` file in your
      repository, it still disrupts some tests (for `find_dotenv`).
- Improve the readability of error messages for some tests.

Changes for users:

- (BREAKING) `dotenv.set_key` and `dotenv.unset_key` used to follow
  symlinks in some situations. This is no longer the case.  For that
  behavior to be restored in all cases, `follow_symlinks=True` should be
  used.
- (BREAKING) In the CLI, `set` and `unset` used to follow symlinks in
  some situations. This is no longer the case.
- (BREAKING) `dotenv.set_key`, `dotenv.unset_key` and the CLI commands
  `set` and `unset` used to reset the file mode of the modified .env
  file to `0o600` in some situations. This is no longer the case: The
  original mode of the file is now preserved. Is the file needed to be
  created or wasn't a regular file, mode `0o600` is used.

…mar#606)

Changes for users:

- (BREAKING) `dotenv run` exits with status code 1 instead of 2 if the command
  provided as argument can't be found.
- `dotenv run` prints a friendly error message instead of a stack trace
  if the command provided as argument can't be found.

Notes:

The existing test case was wrongly testing for that situation: it was
actually observing a "missing env file" error, not a "command not found
error". I thus added an appropriate test case for full coverage.

Co-authored-by: Saurabh Kumar <[email protected]>

…d_dotenv` and `dotenv_values` (theskumar#614)

* Fix: strip UTF-8 BOM from .env files to prevent silent first-variable loss

When a .env file is saved with a UTF-8 BOM (common with JetBrains IDEs
on Windows), the BOM character (\ufeff) was prepended to the first
variable name, making it silently inaccessible via its intended key.

Strip the BOM in Reader.__init__ so all variables are parsed correctly
regardless of whether the file contains a BOM.

Fixes theskumar#637

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

* docs: add changelog entry for BOM fix

---------

Co-authored-by: h1whelan <[email protected]>
Co-authored-by: Claude Opus 4.6 (1M context) <[email protected]>
Co-authored-by: Saurabh Kumar <[email protected]>