Description
After upgrading to Babel 2.17.0, I noticed that pybabel extract no longer respects translator comments (# NOTE:) when the corresponding translatable string spans multiple lines. This was not an issue in Babel 2.16.0, making this a regression.

Steps to Reproduce
Given the following Python code:

'test_string': StringWithMeta(
    # NOTE: Text describing a test string
    string=_(
        'Text string that is on a new line'
    ),
),

Running pybabel extract with Babel 2.17.0 and the parameter --add-comments='NOTE' results in the .pot file missing the comment, whereas in Babel 2.16.0, the comment is correctly extracted.

Expected Behavior
The comment should appear in the .pot file:

#. NOTE: Text describing a test string
msgid "Text string that is on a new line"
msgstr ""

Actual Behavior (Babel 2.17.0 Output)

msgid "Text string that is on a new line"
msgstr ""

The # NOTE: comment is missing.

Additional Findings
Downgrading to Babel 2.16.0 restores the expected behavior.
This only happens when the string spans multiple lines.
Single-line strings still retain their comments.