Handling of "#" in strings

[ericpruitt]

While making some changes to the tmux syntax file for ericpruitt/tmux.vim#26, I noticed that having a line whose first non-whitespace character is "#" seems to result in the entire line being hidden. For example, if I have

set -s @test 'First
            # This prints nothing
this prints # the whole line

Last'

in my tmux configuration then print it in the shell, I got the following output which surprises me:

~$ tmux display-message -p "#{@test}"
First

this prints # the whole line

Last

Do strings support comments or is this a quirk related to parsing #{...}/#(...)/#[...] format strings?