status.diff

diff --git a/lib/bob/builder.rb b/lib/bob/builder.rb
index a316799..b5c2ea3 100644
--- a/lib/bob/builder.rb
+++ b/lib/bob/builder.rb
@@ -5,6 +5,7 @@ module Bob
     def initialize(buildable, commit_id)
       @buildable = buildable
       @commit_id = commit_id
+      @build_status = nil
       @build_output = nil
     end
 
@@ -18,7 +19,8 @@ module Bob
       in_background do
         scm.with_commit(commit_id) do
           buildable.start_building(commit_id, scm.info(commit_id))
-          report_build run_build_script
+          run_build_script
+          report_build 
         end
       end
     end
@@ -31,6 +33,11 @@ module Bob
       @scm ||= SCM.new(buildable.repo_kind, buildable.repo_uri, buildable.repo_branch)
     end
 
+    def build_status
+      raise RuntimeError, "the build hasn't finished yet" if @build_status.nil?
+      @build_status
+    end
+
     def run_build_script
       Bob.logger.debug "Running the build script for #{buildable.repo_uri}"
 
@@ -39,11 +46,12 @@ module Bob
       end
 
       Bob.logger.debug("Ran command '(cd #{scm.working_dir} && #{buildable.build_script} 2>&1)' and got:\n#{build_output}")
-      $?.success?
+
+      @build_status = $?.success?
     end
 
-    def report_build(status)
-      if status
+    def report_build
+      if build_status
         buildable.add_successful_build(commit_id, build_output)
       else
         buildable.add_failed_build(commit_id, build_output)