switch-to-configuration: don't block on flock, see 7a56dda

Author: r-vdp

nixos/modules/system/activation/switch-to-configuration.pl

@@ -95,7 +95,7 @@
 
 make_path("/run/nixos", { mode => oct(755) });
 open(my $stc_lock, '>>', '/run/nixos/switch-to-configuration.lock') or die "Could not open lock - $!";
-flock($stc_lock, LOCK_EX) or die "Could not acquire lock - $!";
+flock($stc_lock, LOCK_EX|LOCK_NB) or die "Could not acquire lock - $!";
 openlog("nixos", "", LOG_USER);
 
 # run pre-switch checks