test/mds: Fix catch by value

Signed-off-by: Adam Emerson <aemerson@redhat.com>

diff --git a/src/test/mds/TestQuiesceDb.cc b/src/test/mds/TestQuiesceDb.cc
index b6319e69c7ef93d748a28a223cfa5621df94ce8f..985325a4e9fa8a43c68dcb22c42edc016ecc965c 100644 (file)
--- a/src/test/mds/TestQuiesceDb.cc
+++ b/src/test/mds/TestQuiesceDb.cc
@@ -1774,7 +1774,7 @@ TEST_F(QuiesceDbTest, QuiesceRootMerge)
     managers.at(mds_gid_t(1))->reset_agent_callback([&agent_map_promise](QuiesceMap& map) -> bool {
       try {
         agent_map_promise.set_value(map);
-      } catch (std::future_error) {
+      } catch (const std::future_error&) {
         // ignore this if we accidentally get called more than once
       }
       return false;