rule file path is always prefixed with "origin prefix" in 2.5.4

[kentxu]

Upgrading from 2.4.1, I noticed all the reroute rules defined in the rule file stopped working.

S3 access log shows the rule file path from Middy Reroute is now prefixed with any prefix defined in the origin.
Here is an example:
const opts={
file: '_redirects/rule1",
rulesBucket: "bucket1"
}

origin is defined as "bucket1/sites"

In 2.4.1, the rule path used is "bucket1/_redirects/rule1"
in 2.5.4, the rule path used is "bucket1/sites/_redirects/rule1"

Is this a bug? The documentation seems to suggest the optional "rulesBucket" and "file" options should form the complete s3 path regardless how the origin is defined.