Clarify logic for environment path handling

src/lib.rs

@@ -118,9 +118,10 @@ use macos as platform;
 ///
 /// [c_rehash]: https://www.openssl.org/docs/manmaster/man1/c_rehash.html
 pub fn load_native_certs() -> CertificateResult {
-    match EnvironmentPaths::from_env().load() {
-        out if !out.certs.is_empty() || !out.errors.is_empty() => out,
-        _ => platform::load_native_certs(),
+    let paths = EnvironmentPaths::from_env();
+    match (&paths.dir, &paths.file) {
+        (Some(_), _) | (_, Some(_)) => paths.load(),
+        (None, None) => platform::load_native_certs(),
     }
 }