Handle missing init script at cluster init
Handle missing init script at cluster init

This patch adds a check in the prereq of LUInitCluster for the existence
of the init script.  This allows a clean abort instead of a stack dump.

Based on a report by admin@steibei.net

Reviewed-by: ultrotter


leshchevds/ganeti,ganeti/ganeti,apyrgio/ganeti,onponomarev/ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti,andir/ganeti,grnet/snf-ganeti,grnet/snf-ganeti,apyrgio/snf-ganeti,apyrgio/ganeti,leshchevds/ganeti,yiannist/ganeti,ganeti/ganeti,onponomarev/ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti,bitemyapp/ganeti,mbakke/ganeti,leshchevds/ganeti,mbakke/ganeti,bitemyapp/ganeti,yiannist/ganeti,mbakke/ganeti,dimara/ganeti,ganeti/ganeti,apyrgio/snf-ganeti,dimara/ganeti,yiannist/ganeti