EllipsisMiddleTruncate exceeds requested width when only the ellipsis fits #722

EllipsisMiddleTruncate returns more characters than the requested width when available_space is 3. It also modifies strings that already fit exactly within the specified width.

Steps to reproduce

from fire import formatting

print(formatting.EllipsisMiddleTruncate('abcdefghij', 3, 80))
# Actual: '...abcdefghij'
# Expected: '...'

print(formatting.EllipsisMiddleTruncate('abcd', 4, 80))
# Actual: '...d'
# Expected: 'abcd'

Cause

The expression text[-second_half_len:] returns the entire string when second_half_len is zero. The no-truncation check also uses < instead of <=.

Expected behavior

Output should respect the available width, and strings that already fit should remain unchanged.

Verification

Reproduced using the implementation from fire/formatting.py.