E101 should ignore multiline strings

[konstin]

In the code below, the whitespace ahead of a and b contains tabs and spaces:

from pathlib import Path


def b():
    Path("my_data.txt").write_text("""
    	a
    		b
    """)

This raises "E101 Indentation contains mixed spaces and tabs", even though this is not indentation but the contents of a multiline string where the leading indentation is user data and not python code. We should ignore multiline strings for E101.

[charliermarsh]

I believe this is a dupe of #7906 where I was asking for a situation in which this would be used in practice.