git flow hotfix start 'strange name'
git flow hotfix finish 'strange name'
Here strange things begin:
Short answer: don't do it.
Long answer: All is implemented in shell scripting currently and spaces are a known danger in that world. Since the hotfix start works fine, I must be forgetting to quote the branch name somewhere in the hotfix finish script, but I didn't have the time to look at it. Of course, as long as Git supports branch names with spaces, git-flow should ideally support them, too, but I don't think there is a big need for it now, so it will be prioritised low.
I'll keep this one open for someone to fix/implement, though.
Actually, git itself does not allow spaces; this lmitation will also apply to the python rewrite, as the error message should be less confusing. Something like
if ! git check-ref-format --branch "$1" &>/dev/null ; then
die "Branch name '$1' is invalid. See git-check-ref-format(1)"