Check redirect locations are valid Uris (#486)

Closes #484

src/into_url.rs

@@ -38,10 +38,14 @@ impl<'a> PolyfillTryInto for &'a String {
     }
 }
 
-pub(crate) fn to_uri(url: &Url) -> ::hyper::Uri {
+pub(crate) fn expect_uri(url: &Url) -> ::hyper::Uri {
     url.as_str().parse().expect("a parsed Url should always be a valid Uri")
 }
 
+pub(crate) fn try_uri(url: &Url) -> Option<::hyper::Uri> {
+    url.as_str().parse().ok()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;