ui: flush before prompting for input with readline
I was using `hg absorb` with Python 3 and noticed that the
prompt was appearing without any output about what would be
done. After I answered the prompt, the output was printed
to stdout.
This appears to be a buffering difference between Python 2
and Python 3.
To work around it, this commit adds an explicit flush() before
calling the raw input function when readline is used.
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true
[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false