title: error "test_input_xml: input file not opened or empty" when run quantum espresso examples
body: <p>I install <em>quantum espresso 6.2</em> and use <em>cygwin</em>. 
  I run example01 to test quantum espresso, which calculate energy and band structure for Si, Al, Cu and Ni. I get an error message as follows:</p>
  
  <pre><code>running the scf calculation for Si...from test_input_xml: input file not opened or empty
  At line 1999 of file read_namelists.f90 (unit = 9, file = 'input_tmp.in')
  Fortran runtime error: End of file
  
  Error termination. Backtrace:
  
  Program received signal SIGSEGV: Segmentation fault - invalid memory reference.
  
  Backtrace for this error:
  from test_input_xml: input file not opened or empty
  At line 1999 of file read_namelists.f90 (unit = 9, file = 'input_tmp.in')
  Fortran runtime error: End of file
  </code></pre>
  
  <p>Could you help me to overcome this problem ?</p>