Fix --foo[=bar] parsing in _parse_help().

bash_completion

@@ -748,7 +748,7 @@ _init_completion()
 _parse_help()
 {
     $1 ${2:---help} 2>&1 | sed -e '/^[[:space:]]*-/!d' -e 's|[,/]| |g' | \
-        awk '{ print $1; if ($2 ~ /^-/) { print $2 } }' | sed -e 's|[<=].*||'
+        awk '{ print $1; if ($2 ~ /^-/) { print $2 } }' | sed -e 's|[<=[].*||'
 }
 
 # This function completes on signal names