fish_key_reader: reuse isatty helper

src/builtins/fish_key_reader.rs

@@ -257,7 +257,7 @@ pub fn fish_key_reader(
         return s;
     }
 
-    if streams.stdin_fd < 0 || unsafe { libc::isatty(streams.stdin_fd) } == 0 {
+    if streams.stdin_fd < 0 || !isatty(streams.stdin_fd) {
         streams.err.appendln("Stdin must be attached to a tty.");
         return Err(STATUS_CMD_ERROR);
     }

src/nix.rs

@@ -41,7 +41,7 @@ pub fn getpid() -> i32 {
 pub fn isatty(fd: i32) -> bool {
     // This returns false if the fd is valid but not a tty, or is invalid.
     // No place we currently call it really cares about the difference.
-    return unsafe { libc::isatty(fd) } == 1;
+    (unsafe { libc::isatty(fd) }) == 1
 }
 
 /// An enumeration of supported libc rusage types used by [`getrusage()`].