[tools] testbot/web: Use AddError() on the special jobs page.

[Francois Gouget]

This is better than direct field access.

Signed-off-by: Francois Gouget 
---
 testbot/web/admin/SpecialJobs.pl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/testbot/web/admin/SpecialJobs.pl b/testbot/web/admin/SpecialJobs.pl
index 2c0bbd1105..d8294c1aaf 100644
--- a/testbot/web/admin/SpecialJobs.pl
+++ b/testbot/web/admin/SpecialJobs.pl
@@ -234,7 +234,7 @@ sub OnSubmit($)

if (@Errors)
   {
-    $self->{ErrMessage} = join("\n", @Errors);
+    $self->AddError(join("\n", @Errors));
     return undef;
   }