Fix test errors that panic outside of the crate.

Rust display the source file to the outside crate, which probably isn't
available in the current workspace.  Next/Prev message was opening a
non-existent file.

Author: ehuss

rust/opanel.py

@@ -79,6 +79,11 @@ def on_data(self, proc, data):
                 appended)
             if m:
                 path = os.path.join(self.base_path, m.group(1))
+                if not os.path.exists(path):
+                    # Panics outside of the crate display a path to that
+                    # crate's source file (such as libcore), which is probably
+                    # not available.
+                    return
                 lineno = int(m.group(2)) - 1
                 # Region columns appear to the left, so this is +1.
                 col = int(m.group(3))

tests/message-order/tests/test_test_output.rs

@@ -52,3 +52,10 @@ fn slow() {
     // This just prints a simple warning.
     std::thread::sleep(std::time::Duration::from_secs(65));
 }
+
+#[test]
+fn panic_outside_crate() {
+    // This (unfortunately) should not show up as an error when running tests
+    // since Rust prints the path to src/libcore/result.rs.
+    Err::<i32, &str>("err").unwrap();
+}