Comment 2 for bug 1646222

I think part of the issue here is the function estimate_kernel_size_in_boot, from utils.py, which does the following:

 92 def estimate_kernel_size_in_boot():
 93 """ estimate the amount of space that the current kernel takes in /boot """
 94 size = 0
 95 kver = os.uname()[2]
 96 for f in glob.glob("/boot/*%s*" % kver):
 97 size += os.path.getsize(f)
 98 return size

The glob ends up including vmlinuz and initrd, which is fine but then DistUpgradeCache.py multiples size by 2. We actually don't need enough free space to accomadate for two of every kernel file in boot though.