Fix in-path sink signature matching

The eventbus payload contained the trailing
/__sink=..., so path matching failed.

system/service/sink.go

@@ -164,7 +164,7 @@ func (svc *sink) ProcessRequest(w http.ResponseWriter, r *http.Request) {
 			body = http.MaxBytesReader(w, r.Body, 32<<10) // 32k limit
 		}
 
-		if err := svc.process(srup.ContentType, w, r, body); err != nil {
+		if err := svc.process(srup, w, r, body); err != nil {
 			return SinkErrProcessingError(sap).Wrap(err)
 		}
 
@@ -281,11 +281,12 @@ func (svc sink) handleRequest(r *http.Request) (*SinkRequestUrlParams, *errors.E
 // b) Max-body-size check might be limited via sink params
 // and io.Reader that is passed is limited w/ io.LimitReader
 //
-func (svc *sink) process(contentType string, w http.ResponseWriter, r *http.Request, body io.Reader) error {
+func (svc *sink) process(srup *SinkRequestUrlParams, w http.ResponseWriter, r *http.Request, body io.Reader) error {
 	var (
-		err error
-		ctx = r.Context()
-		sap = &sinkActionProps{
+		err         error
+		ctx         = r.Context()
+		contentType = srup.ContentType
+		sap         = &sinkActionProps{
 			contentType: contentType,
 		}
 	)
@@ -330,6 +331,14 @@ func (svc *sink) process(contentType string, w http.ResponseWriter, r *http.Requ
 			sanitizedURL.Path = sanitizedURL.Path[i+len(SinkBaseURL):]
 		}
 
+		// Step 3: remove sink suffix if in path
+		if srup.SignatureInPath {
+			i := strings.Index(sanitizedURL.Path, SinkSignUrlParamName)
+			if i > 0 {
+				sanitizedURL.Path = sanitizedURL.Path[0 : i-1]
+			}
+		}
+
 		r.URL = sanitizedURL
 		r.RequestURI = sanitizedURL.String()