utils: T9185: fix ask_yes_no() busy-looping forever on non-tty stdin

commit-confirm (and ~40 other call sites) hang and burn a full CPU core
indefinitely when invoked with stdin that isn't a TTY, e.g. a
non-interactive vbash session (vbash -c "... commit-confirm 10; exit").
input() raises EOFError immediately and repeatedly in that case, and the
except handler in ask_yes_no() looped straight back to input() with no
backoff or exit condition.

Check stdin.isatty() up front and return the default immediately when
it's not a TTY, matching what a user pressing Enter (accepting the
default) would already do interactively.

0 files changed, 0 insertions, 0 deletions