Auto merge of #4884 - tromey:help-to-stdout, r=alexcrichton

Send --help output to stdout

Fixes #4878

Author: bors

src/cargo/lib.rs

@@ -142,7 +142,7 @@ pub fn exit_with_error(err: CliError, shell: &mut Shell) -> ! {
         } else if fatal {
             drop(shell.error(&error))
         } else {
-            drop(writeln!(shell.err(), "{}", error))
+            println!("{}", error);
         }
 
         if !handle_cause(&error, shell) || hide {

tests/search.rs

@@ -277,4 +277,9 @@ fn help() {
                 execs().with_status(0));
     assert_that(cargo_process("help").arg("search"),
                 execs().with_status(0));
+    // Ensure that help output goes to stdout, not stderr.
+    assert_that(cargo_process("search").arg("--help"),
+                execs().with_stderr(""));
+    assert_that(cargo_process("search").arg("--help"),
+                execs().with_stdout_contains("[..] --frozen [..]"));
 }