PR #2503 induced energy derivation from exiting results

[hongriTianqi]

Describe the bug

PR #2503 induced large energy derivation from exiting results, this problem should be fixed.

[dyzheng]

We have tested case of "fco" with large ecutwfc and k-points, there is still large difference between "symmetry 0" and "symmetry 1", it maybe a serious bug.

[dyzheng]

#2626