Spurious help/error output if answer n to Would you like to configure ... as a Pants project? question

[huonw]

If one runs scie-pants in a directory that doesn't have a pants.toml (or one in any ancestor), scie-pants offers to set up, which is cool... but if one says n to this question, it prints out the help output and an error about "population of work directory failed"

No Pants configuration was found at or above /private/var/folders/sv/vd266m4d4lvctgs2wpnhjs9w0000gn/T/tmp.jXKhZ.
Would you like to configure /private/var/folders/sv/vd266m4d4lvctgs2wpnhjs9w0000gn/T/tmp.jXKhZ as a Pants project? (Y/n): n
Error: Isolates your Pants from the elements.

Please select from the following boot commands:

scie-pants
bootstrap-tools
pants
pants-debug
update

You can select a boot command by passing it as the 1st argument or else by setting the SCIE_BOOT environment variable.

ERROR: Failed to establish atomic directory /Users/huon/Library/Caches/nce/aeded33e4c5ab49e551020e735b8d759bd93ba517d04a6046aa60c805ec1bf2e/locks/configure-2aa56b368d34de98a990fbfe7b48c9e4c5a679ba5cc499a6db9e799c1c59e404. Population of work directory failed: Boot binding command failed: exit status: 1

Preferably scie-pants would exit immediately and silently after the n, without the text from Error: Isolates your Pants ... onwards.

Reproducer:

cd $(mktemp -d)

PANTS_BOOTSTRAP_VERSION=report pants
#> 0.10.0

# BUG:
echo n | pants
# output as above

Observed by @engnatha in #263 (comment)