PVS-Studio warning V501 for Firefox

PRBool
nsStyleAnimation::AddWeighted(....)
{
  ...
  if (unit[0] == eCSSUnit_Null || unit[1] == eCSSUnit_Null ||
      unit[0] == eCSSUnit_Null || unit[0] == eCSSUnit_URL) {
    return PR_FALSE;
  }
  ...
}

There seem to be 2 errors at once. The second line in the condition should look like this: unit[0] == eCSSUnit_URL || unit[1] == eCSSUnit_URL.

This suspicious code was found in Firefox project by PVS-Studio static code analyzer.
Warning message is:
V501 There are identical sub-expressions 'unit [0] == eCSSUnit_Null' to the left and to the right of the '||' operator. nsstyleanimation.cpp 1767

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/