Turns out it, and 4 or 5 other older versions were already installed.
I used one of the workarounds here as the basis of the fix, this is it:
in Windows Explorer go to: C:\ProgramData\Package Cache\
search for WinLibJS_CORE.msi
add a column for “Subject” to see the version numbers, then starting with the oldest version, right click and choose uninstall.
I found 2 or 3 were not installed and the remaining 2 or 3 were, then I uninstalled any that were installed.
After uninstalling, right click each file in turn, open file location, navigate up to the parent folder (the GUID), and delete each one in of the folders containing the various versions of WinLibJS_CORE.msi in turn, returning to the search to find the rest and repeat until all are removed.
Finally install the newest version (as I write this, it is supposed to be version 1.0.9651.40228 according to the download page here: http://www.microsoft.com/en-us/download/details.aspx?id=40793 yet when installed it reports to be version 2.1.30324.52
And finally, though I had to choose “Repair” for this install (choices: “Repair or Uninstall), it worked fine and finally there was no outstanding update.