[PATCH] testbot/VMs: Make sure only one process uses a VM at a time.

[Francois Gouget]

The TestBot should already be respecting that rule.
But starting a process to operate on a VM always goes through VM::Run() 
so enforce this rule by checking that the VM's ChildPid field is not 
already set before starting a new process.

Signed-off-by: Francois Gouget 
---
 testbot/lib/WineTestBot/VMs.pm | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/testbot/lib/WineTestBot/VMs.pm b/testbot/lib/WineTestBot/VMs.pm
index 78e066fe9..2bf350435 100644
--- a/testbot/lib/WineTestBot/VMs.pm
+++ b/testbot/lib/WineTestBot/VMs.pm
@@ -154,6 +154,7 @@ use WineTestBot::LibvirtDomain;
 use WineTestBot::Missions;
 use WineTestBot::RecordGroups;
 use WineTestBot::TestAgent;
+use WineTestBot::Utils;

sub _initialize($$)
@@ -374,9 +375,16 @@ sub OnSaved($)
 sub Run($$$$$$)
 {
   my ($self, $NewStatus, $Args, $ChildTimeout, $ChildSetup, $SetupData) = @_;
-
   my $Tool = basename($Args->[0]);

+  if (defined $self->ChildPid)
+  {
+    my $ErrMessage = "Cannot run ". ShArgv2Cmd(@$Args) ." because the ". $self->ChildPid ." process is already using the ". $self->Name ." VM";
+    require WineTestBot::Log;
+    WineTestBot::Log::LogMsg("$ErrMessage\n");
+    return $ErrMessage;
+  }
+
   # There are two $VM->ChildPid race conditions to avoid:
   # - Between the child process and new calls to ScheduleJobs().
   #   We cannot leave setting ChildPid to the child process because then it