Fix Jinja2 escaping of zsh PROMPT in cloud-init template

[ret2libc]

The zsh PROMPT string contains % sequences that Jinja2 interprets as template syntax. Wrap in {% raw %}...{% endraw %} to preserve the literal prompt definition.

[DarkaMaul]

Good catch here - but just a question:

would it be better to do the opposite. Wrap everything in {raw} block and leave outside raw blocks only the part that need interpolation

Because jinja needs escaping also for {{ and {#

[ret2libc]

Wouldn't that be messier? There are many lines where the {{username}} is used, and a few other variables or jinja constructs. I would consider using raw everywhere if there were several places where we just need {% or { but they should not be parsed by jinja. I don't see such occurrences apart from here.

[DarkaMaul]

Wouldn't that be messier? There are many lines where the {{username}} is used, and a few other variables or jinja constructs. I would consider using raw everywhere if there were several places where we just need {% or { but they should not be parsed by jinja. I don't see such occurrences apart from here.

I haven't really considered how messy it would be - I was just scared that the next time we're going to modify this file, we may use an escaped syntax.

But you're right, that's a low probability risk.