Fix scheme setter

> test result: FAILED. 650 passed; 63 failed; 0 ignored; 0 measured

Author: o0Ignition0o

src/lib.rs

@@ -1978,9 +1978,15 @@ impl Url {
     pub fn set_scheme(&mut self, scheme: &str) -> Result<(), ()> {
         let mut parser = Parser::for_setter(String::new());
         let remaining = parser.parse_scheme(parser::Input::new(scheme))?;
-        if !remaining.is_empty()
-            || (!self.has_host() && SchemeType::from(&parser.serialization).is_special())
-        {
+        let new_scheme_type = SchemeType::from(&parser.serialization);
+        let old_scheme_type = SchemeType::from(self.scheme());
+        // Switching from special scheme to non special scheme
+        // and switching from file to non file is not allowed
+        if old_scheme_type != new_scheme_type {
+            return Err(());
+        }
+
+        if !remaining.is_empty() || (!self.has_host() && new_scheme_type.is_special()) {
             return Err(());
         }
         let old_scheme_end = self.scheme_end;

src/parser.rs

@@ -156,7 +156,7 @@ impl fmt::Display for SyntaxViolation {
     }
 }
 
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, PartialEq)]
 pub enum SchemeType {
     File,
     SpecialNotFile,