This also ensures that restoring a backup works when it was created with the wrong upload paths in the time between ab4c0a4970163506e2c72884ff2ba2d8845eb10c (shortly after v2.6.0.beta1) and this fix.
This reverts commit 20780a1eeed56b321daf18ee6bbfe681a51d1bf4.
* SECURITY: re-adds accidentally reverted commit:
03d26cd6: ensure embed_url contains valid http(s) uri
* when the merge commit e62a85cf was reverted, git chose the 2660c2e2 parent to land on
instead of the 03d26cd6 parent (which contains security fixes)
