Improve output of multi-line stderr from local command

[dnephin]

Background

We have a few local commands that run from the Tiltfile before starting resources. We use these commands to output kubernetes yaml that is passed to k8s_yaml. These commands have rather verbose stdout (thousands of lines of yaml), so it's important for us to run these with quiet = True. When one of these commands fail, the stderr is also relatively verbose, it will contain multiple lines to help the user understand why it failed and where the problem occurred.

Problem

We've noticed that it can be difficult to read these multi-line error messages because they are printed using %q. This escapes backslashes and replaces newlines with \n. For example:

stderr: "\nFailed to do some thing:\n at src/myproject/dir/file:2:40\n - reason one\n - reason two\nAlso failed this other thing\n at src/myproject/dir/other:2:40\n - more reasons\n"

Changes in this PR

This PR changes the format string to use %v for this output so that it reads better.

Error in local: command "./script.sh" failed.
error: exit status 1
stdout:
...
stderr:
Failed to do some thing:
 at src/myproject/dir/file:2:40
 - reason one
 - reason two
Also failed this other thing
 at src/myproject/dir/other:2:40
 - more reasons

Does this seem reasonable? Any concerns about where this wouldn't work well?

[nicks]

ya, i'm fine with going with the more simple approach and seeing if anyone complains

[nicks]

LGTM