Avoid double panics when using TempDir in tests

Author: ChrisDenton

library/std/src/sys_common/io.rs

@@ -8,6 +8,7 @@ pub mod test {
     use crate::env;
     use crate::fs;
     use crate::path::{Path, PathBuf};
+    use crate::thread;
     use rand::RngCore;
 
     pub struct TempDir(PathBuf);
@@ -29,7 +30,12 @@ pub mod test {
             // Gee, seeing how we're testing the fs module I sure hope that we
             // at least implement this correctly!
             let TempDir(ref p) = *self;
-            fs::remove_dir_all(p).unwrap();
+            let result = fs::remove_dir_all(p);
+            // Avoid panicking while panicking as this causes the process to
+            // immediately abort, without displaying test results.
+            if !thread::panicking() {
+                result.unwrap();
+            }
         }
     }