Don't strip out content that looks like the field name from the middle of a field

CHANGELOG.rdoc

@@ -10,6 +10,7 @@
 * #868 - Use the Ruby19.charset_encoder when decoding message bodies (kjg)
 * #866 - Support decoding message bodies with non-Ruby-standard charsets (jeremy)
 * #907 - Mail::ContentDispositionField should work with nil value (kjg)
+* #719 - Fix for when header content looks like field name (kjg)
 
 == Version 2.6.3 - Mon Nov 3 23:53 +1100 2014 Mikel Lindsaar <mikel@reinteractive.net>
 

lib/mail/fields/common/common_field.rb

@@ -44,7 +44,7 @@ def strip_field(field_name, value)
       if value.is_a?(Array)
         value
       else
-        value.to_s.sub(/#{field_name}:\s+/i, EMPTY)
+        value.to_s.sub(/\A#{field_name}:\s+/i, EMPTY)
       end
     end
 

spec/mail/fields/common/common_field_spec.rb

@@ -66,11 +66,20 @@
       expect(field.encoded).to eq result
       expect(field.decoded).to eq value
     end
-
+
+  end
+
+  context "when including the field name" do
+    it "does not strip out content that looks identitcal to the field name" do
+      field = Mail::SubjectField.new("Subject: Subject: for your approval")
+      expect(field.decoded).to eq("Subject: for your approval")
+    end
   end
 
-  it "does not strip out content that looks identitcal to the field name" do
-    field = Mail::SubjectField.new("Subject: Subject: for your approval")
-    expect(field.decoded).to eq("Subject: for your approval")
+  context "when not including the field name" do
+    it "does not strip out content that looks identitcal to the field name" do
+      field = Mail::SubjectField.new("This is an important subject: here")
+      expect(field.decoded).to eq("This is an important subject: here")
+    end
   end
 end