Debug: 1: looking for foo without backtracking
Debug: 1.1: simple apply H on foo, 1 subgoal(s)
Debug: 1.1-1 : foo
Debug: 1.1-1: looking for foo without backtracking
Debug: 1.1-1.1: simple apply H on foo, 1 subgoal(s)
Debug: 1.1-1.1-1 : foo
Debug: 1.1-1.1-1: looking for foo without backtracking
Debug: 1.1-1.1-1.1: simple apply H on foo, 1 subgoal(s)
Debug: 1.1-1.1-1.1-1 : foo
Debug: 1.1-1.1-1.1-1: looking for foo without backtracking
Debug: 1.1-1.1-1.1-1.1: simple apply H on foo, 1 subgoal(s)
Debug: 1.1-1.1-1.1-1.1-1 : foo
Debug: 1.1-1.1-1.1-1.1-1: looking for foo without backtracking
Debug: 1.1-1.1-1.1-1.1-1.1: simple apply H on foo, 1 subgoal(s)
Debug: 1.1-1.1-1.1-1.1-1.1-1 : foo
The command has indeed failed with message:
Tactic failure: Proof search reached its limit.