v0.4.11
Supported a strange rule of a braced parameter.
π£ echo ${BASH_VERSION}
0.4.11-rusty_bash
π£ echo ${BASH_VERSION-} #OK
0.4.11-rusty_bash
π£ echo ${BASH_VERSION-aaaaa} #OK
0.4.11-rusty_bash
π£ echo ${BASH_VERSION -aaaaa} #NG
sush: ${BASH_VERSION -aaaaa}: bad substitution