I think the control flow in this function is complicated and confusing,
largely due to the use of two booleans `print_formatted` and
`fallback_to_println` that are set in multiple places and then used to
guide proceedings.
As well as hurting readability, this leads to at least one bug: if the
`write_termcolor_buf` call fails and the pager also fails, the function
will try to print color output to stdout, but that output will be empty
because `write_termcolor_buf` failed. I.e. the `if fallback_to_println`
body fails to check `print_formatted`.
This commit rewrites the function to be neater and more Rust-y, e.g. by
putting the result of `write_termcolor_buf` into an `Option` so it can
only be used on success, and by using `?` more. It also changes
terminology a little, using "pretty" to mean "formatted and colorized".
The result is a little shorter, more readable, and less buggy.
525e1919f7