I'm having this issue running Jessie with my boot and root partitions on LVM. This workaround works for me without needing a rootdelay= kernel parameter: add "lvm pvscan" and "lvm vgscan" to /usr/share/initramfs-tools/scripts/local-top/lvm2 and run sudo update-initramfs.
I don't know if both commands are necessary, but they are sufficient. That file comes from the package lvm2. I'm using lvm2:amd64 2.02.98-6+b1.
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