convert-ly dies on invalid input

[Werner LEMBERG]

Consider this (incorrect) input file `p.ly', consisting of a single
line:

  \version "2.14."

convert-ly bombs out with

  convert-ly (GNU LilyPond) 2.15.15
  convert-ly: Processing `p.ly'... 
  Traceback (most recent call last):
    File "/usr/local/bin/convert-ly", line 368, in <module>
      main ()
    File "/usr/local/bin/convert-ly", line 355, in main
      do_one_file (f)
    File "/usr/local/bin/convert-ly", line 260, in do_one_file
      from_version = str_to_tuple (guess)
    File "/usr/local/bin/convert-ly", line 172, in str_to_tuple
      return tuple ([int(n) for n in s.split ('.')])
  ValueError: invalid literal for int() with base 10: ''

Any chance to fix convert-ly so that it shows the problematic line
number in the user's input file?


    Werner