Can't escape closing brace with backslash or single quotes in parameter expansion

[Crestwave]

Required for #679; thought I was done, but running it on my other computer triggered this. The latter is probably #291, but the former seems to be another (possibly related) issue; backslash escaping does work with other characters.

$ var='$foo'
$ echo "${var#$foo}"
$foo
$ echo "${var#\$foo}"

$ var='}'
$ echo "${var#}}"
}}
$ echo "${var#\}}"

$ echo "${var#'}'}"

$ echo "${var#"}"}"

osh$ var='$foo'
osh$ echo "${var#$foo}"
$foo
osh$ echo "${var#\$foo}"

osh$ var='}'
osh$ echo "${var#}}"
}}
osh$ echo "${var#\}}"
}}
osh$ echo "${var#'}'}"
}'}
osh$ echo "${var#"}"}"

[andychu]

Fixed at the same time as #291! woohoo