Using package resizegather leads to extra vertical space inside mdframed equations

When I try to add package resizegather, extra vertical space is added into mdframed equations. By gradually truncating the code, I found that commenting package resizegather would fix the problem. See figure below. But I have no idea, what is behind that. I found similar issues described in tasks:

• mdframed package + align gives extra vertical space
• Extra vertical space inside mdframed theorem environment

but it didn’t help

MNWE:

documentclass{scrbook}

usepackage{mdframed}
usepackage{amsmath}
usepackage{resizegather}    
usepackage{blindtext}

begin{document}
  chapter{My title test 7}
    blindtext  
    begin{mdframed}
      begin{equation}label{mai:eq1}
        boxed{int f(x) dx = F(x) + c}
      end{equation}
    end{mdframed}
    blindtext  
end{document}

documentclass{scrbook}

usepackage{mdframed}
usepackage{amsmath, nccmath}
usepackage{resizegather}
usepackage{blindtext}

begin{document}
  chapter{My title test 7}
    blindtext
    begin{mdframed}useshortskip
      begin{equation}label{mai:eq1}
        boxed{int f(x) dx = F(x) + c}
      end{equation}
    end{mdframed}
    blindtext
end{document}