Issue #3186415 by phenaproxima, Charlie ChX Negyesi, walangitan, pianomansam,...

Issue #3186415 by phenaproxima, Charlie ChX Negyesi, walangitan, pianomansam, dan2k3k4, Al Munnings, larowlan, philltran, cilefen, longwave, alexpott, pookmish, kaynen, Lendude, Gábor Hojtsy, rlnorthcutt, ksenzee: Make oEmbed resource fetcher more tolerant of unexpected Content-Type headers

(cherry picked from commit 167686b8)