PanicSentinel: only set flag if dropped while panicking

aquatic_common/src/lib.rs

@@ -55,14 +55,16 @@ pub struct PanicSentinel(Arc<AtomicBool>);
 
 impl Drop for PanicSentinel {
     fn drop(&mut self) {
-        let already_triggered = self.0.fetch_or(true, Ordering::SeqCst);
+        if ::std::thread::panicking() {
+            let already_triggered = self.0.fetch_or(true, Ordering::SeqCst);
 
-        if !already_triggered {
-            if unsafe { libc::raise(15) } == -1 {
-                panic!(
-                    "Could not raise SIGTERM: {:#}",
-                    ::std::io::Error::last_os_error()
-                )
+            if !already_triggered {
+                if unsafe { libc::raise(15) } == -1 {
+                    panic!(
+                        "Could not raise SIGTERM: {:#}",
+                        ::std::io::Error::last_os_error()
+                    )
+                }
             }
         }
     }