* Remove possibility of using remote repositories;

  * Search for production signing keys with fallback for testing;

  * Fix issue where packages were upgraded at the wrong time.

autobuilder: Use variable for Git branch

See merge request !7

This allows easier selection of which branch to autobuild.

Unmount mounts in reverse order of mounts. Precisely, filesystems before special devices. Fixes #12.

config: Ensure CPPFLAGS is empty by default

See merge request !6

Some configurations use "-Os -fomit-frame-pointer" as a default CPPFLAGS.
This is incorrect, and at least in the case of system/python3, causes a
miscompile on ppc64.  This is the true root cause of adelie/packages#451.

We set it empty in common to ensure that arch-specific overrides can still
happen; specifically, if we ever do the once-drafted Pentium 4 spin, we
may need some CPPFLAGS for the SSE2 stuff.

autobuilder: Export SHELL in build env

Closes #8

See merge request !5

Closes: #8

autobuilder: Fix generation of /etc/fstab

Closes #4

See merge request !4

File name should be /etc/fstab, not /etc.fstab.

Fixes: d3cc341d ("Add dummy '/etc/fstab' to rootfs environments. Fixes #4.")

autobuilder: use curl when available over wget

See merge request !2