Docstring reformatting causes line to be too long

[adamjstewart]

Describe the bug

Black is overzealous about reformatting docstrings to a single line, and can cause the resulting line to be longer than the line length limit.

To Reproduce

For example, take this code:

def f():
    """89 123456789 123456789 123456789 123456789 123456789 123456789 123456789 12345678
    """

The first line of this docstring is exactly 88 characters. After blackening this code, this results in:

def f():
    """89 123456789 123456789 123456789 123456789 123456789 123456789 123456789 12345678"""

The line is now 91 characters, and flake8 complains.

Expected behavior

Honestly, I wouldn't expect black to reformat docstrings at all. But I definitely wouldn't expect it to reformat to the point where style-compliant code becomes non-style-compliant.

Environment

• Black's version: 22.10.0, main
• OS and Python version: macOS 12.6, Python 3.9.13

Additional context

This appears to be a regression of the same bug reported in #1632 and #2274.

[felix-hilden]

With the "preview" toggle enabled, this is fixed. Also worth mentioning that we're discussing the exact opposite behavior in #3320.

[adamjstewart]

Thanks, glad to know it's already been fixed!