print traceback from cli_handle_exception

Instead of only printing the exception info, also print the
traceback.

python/lsst/daf/butler/cli/utils.py

@@ -20,7 +20,9 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import click
+import io
 import os
+import traceback
 from unittest.mock import MagicMock
 
 from ..core.utils import iterable
@@ -181,5 +183,9 @@ def cli_handle_exception(func, *args, **kwargs):
         return
     try:
         return func(*args, **kwargs)
-    except Exception as err:
-        raise click.ClickException(err)
+    except Exception:
+        msg = io.StringIO()
+        msg.write("An error occurred during command execution:\n")
+        traceback.print_exc(file=msg)
+        msg.seek(0)
+        raise click.ClickException(msg.read())

tests/test_cliCmdConfigDump.py

@@ -95,7 +95,7 @@ def test_invalidSubset(self):
             # test dumping to stdout:
             result = runner.invoke(butler.cli, ["config-dump", "here", "--subset", "foo"])
             self.assertEqual(result.exit_code, 1)
-            self.assertEqual(result.output, "Error: 'foo not found in config at here'\n")
+            self.assertIn("Error: 'foo not found in config at here'", result.output)
 
 
 if __name__ == "__main__":