Add quotes around format strings for compatibility with msys2 (git bash)

[byron-hawkins]

Basic commands such as tmux list-sessions currently hang when running in an msys2 shell (ie.g., git bash). For some reason, this can be resolved by adding quotes around the format strings. A 3-liner patch is attached. Have not tested this change on other platforms, and also have not thoroughly tested for additional cases where quotes may be necessary for msys2 compatibility.

msys2-compatibility-quoting.patch

[tony]

Thanks, to clarify, are you using psmux?