Failures in "after" scripts do not currently result in bootstrap
failures since "find" ignores the exit code of commands that it
executes.
There are no simple options in "find" to both propagate non-0 exit
statuses of executed commands and also abort its command execution
sequence in such an event. As such, use "find" only for listing
script names and otherwise use a simple loop to execute them.
While at it, execute scripts in numerical order according to their
basename. This gives consumers control over the execution order of
their scripts. For example, 50-sign.sh will be executed before
51-upload.sh.
The sysrq shutdown trigger takes some time to fully shut down the system,
during which init is expected to continue running. Since after.sh is the
last step in our init, if it quits before shutdown is complete, Linux will
panic with "Attempted to kill init".
Add an infinite loop after shutdown is issued via sysrq to prevent this.
