[downloader/fragment] Set final file's mtime according to last fragment's Last-Modified header (closes #11718, closes #18384, closes #27138)
[downloader/fragment] Set final file's mtime according to last fragment's Last-Modified header (closes #11718, closes #18384, closes #27138)

yan12125/youtube-dl,ozburo/youtube-dl,spvkgn/youtube-dl,rg3/youtube-dl,Tatsh/youtube-dl,spvkgn/youtube-dl,ozburo/youtube-dl,yan12125/youtube-dl,rg3/youtube-dl,Tatsh/youtube-dl