Pasting two slash commands at once folds the second into the first command's arguments

Pasting a two-line block where each line is its own slash command runs only the first command, with the rest of the paste swallowed into its arguments.

Repro:

1. Paste this as a single block:

``
/plugin marketplace add grepsedawk/kevin
/plugin install kevin@kevin
``

1. Submit.

Expected: two commands run in order, or the input is recognized as two commands.

Actual: the whole paste becomes arguments to /plugin marketplace add, so it tries to clone grepsedawk/kevin /plugin install kevin as one URL:

fatal: unable to access 'https://github.com/grepsedawk/kevin /plugin install kevin.git/': URL rejected: Malformed input to a URL function

Workaround is pasting each command separately. It feels intuitive that a multi-line paste of commands should just run them in sequence.