Summary:

The second kernel booted (see NOTE below) and I was able to 
copy /proc/vmcore, although I did see the following error at
the end of the copy:
	cp: reading '/proc/vmcore': Invalid argument 

NOTE: I saw the following error when booting both the first and
second kernels:
	Waiting for device /dev/sda2 to appear: .....not found
        ... lots of device nodes printed ...
	No root device found; exiting to /bin/sh
	sh: can't access tty; job control turned off
	$ 
The kernel completed booting when I exited from /bin/sh.
I don't think this problem is related to kexec or kdump.