Fix AM format_paragraph helper method if a first word is long

actionmailer/lib/action_mailer/mail_helper.rb

@@ -41,7 +41,7 @@ module ActionMailer
       sentences = [[]]
 
       text.split.each do |word|
-        if (sentences.last + [word]).join(' ').length > len
+        if sentences.first.present? && (sentences.last + [word]).join(' ').length > len
           sentences << [word]
         else
           sentences.last << word

actionmailer/test/mail_helper_test.rb

@@ -22,6 +22,14 @@ class HelperMailer < ActionMailer::Base
     end
   end
 
+  def use_format_paragraph_with_long_first_word
+    @text = "Antidisestablishmentarianism is very long."
+
+    mail_with_defaults do |format|
+      format.html { render(:inline => "<%= format_paragraph @text, 10, 1 %>") }
+    end
+  end
+
   def use_mailer
     mail_with_defaults do |format|
       format.html { render(:inline => "<%= mailer.message.subject %>") }
@@ -81,6 +89,11 @@ class MailerHelperTest < ActionMailer::TestCase
     assert_match " But soft! What\r\n light through\r\n yonder window\r\n breaks?", mail.body.encoded
   end
 
+  def test_use_format_paragraph_with_long_first_word
+    mail = HelperMailer.use_format_paragraph_with_long_first_word
+    assert_equal " Antidisestablishmentarianism\r\n is very\r\n long.", mail.body.encoded
+  end
+
   def test_use_block_format
     mail = HelperMailer.use_block_format
     expected = <<-TEXT