show command doesn't obey --dir argument

[HT154]

Is this a BUG REPORT or FEATURE REQUEST?:
/kind bug

What happened:
I'm running ks show --dir /absolute/path/to/app. When I'm not in the app directory, I get an error ERROR finding app root from starting path: : unable to find ksonnet project

Every other command works correctly: apply, diff, delete, env, etc.

If I switch to the app directory and run show command, it works as expected. This also occurs with relative paths, but my original test case used an absolute path.

What you expected to happen:
Show command obeys the --dir arg and runs successfully

How to reproduce it (as minimally and precisely as possible):

ks init test

# these print the error shown above
ks --dir test show default
ks show --dir test default
ks show default --dir test

# this works
(cd test; ks show default)

Environment:

• ksonnet version (use ks version):

ksonnet version: 0.13.0
jsonnet version: v0.11.2
client-go version: kubernetes-1.10.4

• Kubernetes version (use kubectl version):

Client Version: version.Info{Major:"1", Minor:"13", GitVersion:"v1.13.0", GitCommit:"ddf47ac13c1a9483ea035a79cd7c10005ff21a6d", GitTreeState:"clean", BuildDate:"2018-12-03T21:04:45Z", GoVersion:"go1.11.2", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"11", GitVersion:"v1.11.5", GitCommit:"753b2dbc622f5cc417845f0ff8a77f539a4213ea", GitTreeState:"clean", BuildDate:"2018-11-26T14:31:35Z", GoVersion:"go1.10.3", Compiler:"gc", Platform:"linux/amd64"}