libpng-1.6.11beta04 is available from
ftp://ftp.simplesystems.org/pub/png-group/src/libpng16
and from
http://libpng.sf.net

Version 1.6.11beta04 [April 19, 2014]
  Made progressive reading of interlaced images consistent with the
    behavior of the sequential reader and consistent with the manual,
    by moving some code out of the PNG_READ_INTERLACING_SUPPORTED blocks.
    The row_callback now receives the proper pass number and unexpanded rows,
    when png_combine_row is not used or not built,
  Allow PNG_sRGB_PROFILE_CHECKING = (-1) to mean no sRGB profile checking.

Glenn