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.
--- a/mercurial/ui.py Fri Nov 01 21:46:34 2019 -0700
+++ b/mercurial/ui.py Sat Nov 02 15:33:39 2019 -0700
@@ -1564,6 +1564,7 @@
# - http://bugs.python.org/issue12833
with self.timeblockedsection(b'stdio'):
if usereadline:
+ self.flush()
prompt = encoding.strfromlocal(prompt)
line = encoding.strtolocal(pycompat.rawinput(prompt))
# When stdin is in binary mode on Windows, it can cause