Fixes an issue where a nested block would be decoded incorrectly, the
body of the last decoded block overwrites the previously decoded ones.
This was caused by the block being assigned on the stack in the for
loop; when the block is converted to a *hcl.Block, the pointer to Body
will always point to the same block. This caused decoding a new block to
overwrite the bodies of any previously decoded blocks.
b12d28fd16