Variables: fixed non-indexed access of prefix vars (ticket #600). Previously, a configuration like location / { ssi on; ssi_types *; set $http_foo "bar"; return 200 '<!--#echo var="http_foo" -->\n'; } resulted in NULL pointer dereference in ngx_http_get_variable() as the variable was explicitly added to the variables hash, but its get_handler wasn't properly set in the hash. Fix is to make sure that get_handler is properly set by ngx_http_variables_init_vars().