Consider assuming that line numbers are at least two digits

[Wilfred]

Since the vast majority of files have at least 10 lines, it might improve alignment.

foo.py --- 1/2 --- Python
1 1
2   new_import()

foo.py --- 2/2 --- Python
11 12
12 13 other_change()

[Wilfred]

A better heuristic might be looking at the line number of the last change in the file.