ui: check EOF of getpass() response read from command-server channel...
ui: check EOF of getpass() response read from command-server channel
readline() returns '' only when EOF is encountered, in which case, Python's
getpass() raises EOFError. We should do the same to abort the session as
"response expected."
This bug was reported to
https://bitbucket.org/tortoisehg/thg/issues/4659/