base-files, glibc lockstep migration blocking bug

[Julian Andres Klode]

With the new changes I'm uploading, taken from Helmut's patches on Debian bug tracker, base-files will own the /lib64 symlink, and /lib64 in libc6 will move to /usr/lib64.

Special care has been taken to not break upgrades: You can upgrade the two in any order.

However, debootstrap requires both packages to be at a matching version:

1. If base-files migrates first, the old libc6 would fail to unpack
2. If glibc migrates first, and is bootstrapped before base-files, we do not end up with the /lib64 symlink at all because debootstrap only *moves* an existing /lib64 (which now is no longer present).

Since upgrades are fine due to having the symlink already, we do not want to solve this by introducing dependencies: We could have added mutual Depends or Breaks, but they would have required temporarily deconfiguring one of the packages to unpack the other on upgrades.

Hence we'll mark this bug as block-proposed and remove the tag once both are ready to land.

[Julian Andres Klode (juliank)]

apt and bzip2 have migrated, so we are ready to land them in the next britney run.