Stream URL file from source; write file as we receive it.  #14.
Stream URL file from source; write file as we receive it.  #14.

This shifts responsibility to wpull for parsing the URL file; all we do
is fetch it.

Potential issue: I'm not sure if Response.iter_content bypasses
transfer-encoding handling.  If it does, then we'll have to use a code
path that doesn't.  (Another possibility: just shell out to curl...)

JesseWeinstein/ArchiveBot,falconkirtaran/ArchiveBot,JesseWeinstein/ArchiveBot,Asparagirl/ArchiveBot,falconkirtaran/ArchiveBot,Asparagirl/ArchiveBot,falconkirtaran/ArchiveBot,emijrp/ArchiveBot,Frogging101/ArchiveBot,Frogging101/ArchiveBot,ArchiveTeam/ArchiveBot,Frogging101/ArchiveBot,emijrp/ArchiveBot,emijrp/ArchiveBot,JesseWeinstein/ArchiveBot,Asparagirl/ArchiveBot,Frogging101/ArchiveBot,Asparagirl/ArchiveBot,emijrp/ArchiveBot,falconkirtaran/ArchiveBot,JesseWeinstein/ArchiveBot,ArchiveTeam/ArchiveBot,ArchiveTeam/ArchiveBot,ArchiveTeam/ArchiveBot,ArchiveTeam/ArchiveBot,Frogging101/ArchiveBot,emijrp/ArchiveBot,JesseWeinstein/ArchiveBot,falconkirtaran/ArchiveBot,Asparagirl/ArchiveBot