/path/abcd works, but /path/ab%2Fcd ➔ "invalid path for static asset"

I pass IANA timezone information to the server using a GET request. It surprises me that while

/timezone/Europe*Athens works as expected
/timezone/Europe%2FAthens results in an “invalid path for static asset” error

It seems that the forward slash (%2F) is unescaped prior to the checking of the route’s validity. The workaround is easy, I am just wondering whether this behaviour is normal. Shouldn’t Phoenix/Plug be configured in a way that allows a common JS method such as encodeURIComponent to pass data to the server without further tinkering?