Print truncated in number of lines, not chars?

[ethanhs]

Looking at python/mypy#12901 it occurs to me since our errors are more line-oriented, it may make more sense to print the number of lines truncated instead of number of characters.

For example, in that PR, it tells me nothing that there are 3M truncated characters (well, other than there are a lot more errors) but number of lines would give a better approximate number of errors reported.

[hauntsaninja]

Good point, fixed in python/mypy#12910 and python/typeshed#7993

[ethanhs]

Thanks!