Handle error being set to a raw string

* Ignore vim swp files

.gitignore

@@ -1,2 +1,3 @@
 Gemfile.lock
-pkg
+pkg
+*swp

lib/batchy/batch.rb

@@ -117,7 +117,13 @@ def error
       return err if err.blank?
 
       backtrace = read_attribute(:backtrace)
-      err.set_backtrace(backtrace)
+      if err.respond_to?(:set_backtrace)
+        err.set_backtrace(backtrace) 
+      else
+        def err.backtrace
+          nil
+        end
+      end
 
       err
     end

lib/batchy/version.rb

@@ -1,3 +1,3 @@
 module Batchy
-  VERSION = "0.2.3"
+  VERSION = "0.2.4"
 end

spec/batch_spec.rb

@@ -137,6 +137,15 @@
     @batch.error.backtrace.should == backtrace
   end
 
+  it 'should be able to handle a string in the error field' do
+    @batch.start
+    @batch.error = "This is an error"
+    @batch.finish!
+
+    @batch.error.should == "This is an error"
+    @batch.error.backtrace.should be_nil
+  end
+
   describe 'parents' do
     it 'should set its parent' do
       child = FactoryGirl.create(:batch)