Prefixrouter accepts repeated prefixes

[bastianccm]

The prefixrouter accepts requests to /prefix/prefix/ as / for /prefix

For full prefix this seems to be fine (inkl. host)

by @Ompluscator

the reason why flamingo doesn't recognize here /prefix/prefix is probably because BASE_PATH is now full domain "https://example.com/prefix", not just "/prefix" ^^ maybe Mr @bastian.ike can check this issue with flamingo core router