linbo_cmd initcache_format has a wrong return code on failure

[dorianim]

When running linbo_cmd initcache_format while the /cache partition is still busy, the formatting fails, but there is still a 0 return code. Steps to reproduce: (on linbo console)

1. linbo_cmd mountcache
2. cd /cache
3. linbo_cmd initcache_format 10.9.0.1 /dev/sdX rsync test.cloop
4. echo "$?"

The problem probably lies here, as the return code of format seems to be ignored. https://github.com/linuxmuster/linuxmuster-linbo/blob/4759d9e24f02e3b06b8365015a97fee8d3a3a13e/linbofs/usr/bin/linbo_cmd#L3243