Nixpkgs: nixos-rebuild fails, saying "GRUB_ENABLE_CRYPTODISK=y" is missing in grub

[peti]

nixos-rebuild boot fails on my machine while trying to run grub:

# nixos-rebuild boot
building Nix...
building the system configuration...
updating GRUB 2 menu...
installing the GRUB 2 boot loader on /dev/disk/by-id/ata-SAMSUNG_MMCQE28G8MUP-0VA_SE936B7450...
Installing for i386-pc platform.
You have a memory leak (not released memory pool):
 [0x1b883c0] dtree
Internal error: Unreleased memory pool(s) found.
You have a memory leak (not released memory pool):
 [0x1b883c0] dtree
Internal error: Unreleased memory pool(s) found.
You have a memory leak (not released memory pool):
 [0x1b883c0] dtree
Internal error: Unreleased memory pool(s) found.
You have a memory leak (not released memory pool):
 [0x1b883c0] dtree
Internal error: Unreleased memory pool(s) found.
You have a memory leak (not released memory pool):
 [0x1b883c0] dtree
Internal error: Unreleased memory pool(s) found.
You have a memory leak (not released memory pool):
 [0x1b883c0] dtree
Internal error: Unreleased memory pool(s) found.
You have a memory leak (not released memory pool):
 [0x1b883c0] dtree
Internal error: Unreleased memory pool(s) found.
You have a memory leak (not released memory pool):
 [0x1b883c0] dtree
Internal error: Unreleased memory pool(s) found.
You have a memory leak (not released memory pool):
 [0x1b883c0] dtree
Internal error: Unreleased memory pool(s) found.
You have a memory leak (not released memory pool):
 [0x1b8af20] dtree
Internal error: Unreleased memory pool(s) found.
You have a memory leak (not released memory pool):
 [0x1b8af20] dtree
Internal error: Unreleased memory pool(s) found.
You have a memory leak (not released memory pool):
 [0x1b8af20] dtree
Internal error: Unreleased memory pool(s) found.
/nix/store/53xshnldp06n3cqfjg586lzia9hcak2f-grub-2.x-2015-11-16/sbin/grub-install: error: attempt to install to encrypted disk without cryptodisk enabled. Set `GRUB_ENABLE_CRYPTODISK=y' in file `/nix/store/53xshnldp06n3cqfjg586lzia9hcak2f-grub-2.x-2015-11-16/etc/default/grub'.
/nix/store/zldbbngl0f8g5iv4rslygxwp0dbg1624-install-grub.pl: installation of GRUB on /dev/disk/by-id/ata-SAMSUNG_MMCQE28G8MUP-0VA_SE936B7450 failed
warning: error(s) occurred while switching to the new configuration

I'm using master at 8a0f2e7025d1682f793f67f9364564851448479e with LUKS encryption enabled for the root disk.

[hrdinka]

This error usually occurs when the device that grub installs to isn't mounted. Please check if /boot is mounted. If it is not it might got unmounted due https://github.com/NixOS/nixpkgs/issues/11480. I had this same issue.

[peti]

Duplicate of https://github.com/NixOS/nixpkgs/issues/11480. Run mount /boot to remedy the issue to the extend that nixos-rebuild boot can succeed again.