Pushing or trampling should reveal mimics

[PowerWyrm]

"You see a Potion of Speed. The Fire Elemental tramples over the Potion Mimic."

"You see a Potion of Speed. The 2-headed hydra pushes past the Potion Mimic. You see a Potion of Speed."

Easy fix: use become_aware() in process_monster().

if (kill_ok || move_ok) {
		/* Get the names of the monsters involved */
		char m1_name[80];
		char n_name[80];
		monster_desc(m1_name, sizeof(m1_name), m_ptr, MDESC_IND1);
		monster_desc(n_name, sizeof(n_name), n_ptr, MDESC_IND1);

		/* Allow movement */
		do_move = TRUE;

		/* Reveal mimics */
		if (is_mimicking(n_ptr))
                	become_aware(n_ptr);

		/* Monster ate another monster */
		if (kill_ok) {
			/* Note if visible */
			if (m_ptr->ml && (m_ptr->mflag & (MFLAG_VIEW)))
			msg("%s tramples over %s.", m1_name, n_name);

			delete_monster(ny, nx);
		} else {
			/* Note if visible */
			if (m_ptr->ml && (m_ptr->mflag & (MFLAG_VIEW)))
			msg("%s pushes past %s.", m1_name, n_name);
		}
	}

[takkaria]

Fixed in ​https://github.com/angband/angband/pull/303