Single-line imports are unnecessarily wrapped

[taylordotfish]

Imports that could fit on a single line are unnecessarily wrapped:

/* 50 characters:
0        1         2         3         4         5
12345678901234567890123456789012345678901234567890
*/
use aaaaaaaaa::{bbbbbbbbb, ccccccccc, ddddddddd};

After rustfmt --config max_width=50:

/* 50 characters:
0        1         2         3         4         5
12345678901234567890123456789012345678901234567890
*/
use aaaaaaaaa::{
    bbbbbbbbb, ccccccccc, ddddddddd,
};

The use declaration is only 49 characters but gets wrapped anyway. This also happens with the default max_width of 100 (use declarations > 98 characters get wrapped).