Fix dotenv get exiting with code 1 for empty string values

[ShamikOfficial]

Fixes #699.

Problem

dotenv get KEY uses if stored_value: so an empty string is treated as missing and the command exits with code 1 — the same as an absent key.

>>> from dotenv import set_key, get_key
>>> set_key(".env", "EMPTY", "")
>>> get_key(".env", "EMPTY")   # library API is fine
''
>>> # dotenv get EMPTY  -> exit code 1

Empty values (KEY= / KEY="") are valid; only the CLI was wrong.

Fix

Exit only when the key is absent or the stored value is None (bare key with no value). Empty strings are echoed and exit 0.

Tests

• New test_get_empty_string_value pins exit code 0 and a blank line of output for a=.
• Existing get tests still pass.

pytest tests/test_cli.py::test_get_existing_value tests/test_cli.py::test_get_empty_string_value tests/test_cli.py::test_get_non_existent_value — 3 passed.

[theskumar]

Thanks @ShamikOfficial, the fix looks right. It matches get_key, which returns '' for KEY= and None for a bare KEY. I pushed two commits on top of yours without changing your commits:

• Merge main: fixes the CHANGELOG.md conflict with Fix variable expansion in dotenv run --no-override #698. Both link lines are kept and your entry is unchanged.
• test_get_value_without_equals: a bare a line still exits 1 with no output.

Why the extra test: I tried a few deliberately broken versions of get. test_get_empty_string_value catches the original truthiness bug, but two plausible regressions got past the existing tests:

Mutant	Caught before	Caught after
if not values.get(key): (original bug)	✅	✅
if key not in values: (drops the None check, prints None)	❌	✅
never sys.exit(1)	❌	✅

Locally: 260 passed, ruff check/ruff format --check clean, mypy --python-version 3.10 and 3.14 clean.