passwd: Allow root to always change passwords

Previously root would need to know its own password. On Linux root can
change its own password without needing to enter its own password. It
can do so on Redox OS already anyway by directly editing /etc/shadow.

src/bin/passwd.rs

@@ -103,11 +103,13 @@ fn main() {
     stdout.flush().r#try(&mut stderr);
 
     let mut verified = false;
-    if user.is_passwd_blank() {
+    if uid == 0 {
         verified = true;
-    } else if user.is_passwd_unset() && uid != 0 {
+    } else if user.is_passwd_blank() {
+        verified = true;
+    } else if user.is_passwd_unset() {
         verified = false;
-    } else if user.uid == uid || uid != 0 {
+    } else {
         stdout.write_all(b"current password: ").r#try(&mut stderr);
         stdout.flush().r#try(&mut stderr);
 
@@ -117,8 +119,6 @@ fn main() {
 
             verified = user.verify_passwd(&password)
         }
-    } else {
-        verified = true;
     }
 
     if !verified {