Failing test for messed up P image on write only format

.travis.yml

@@ -14,7 +14,7 @@ python:
   - 3.4
 
 install:
-  - "sudo apt-get -qq install libfreetype6-dev liblcms2-dev python-qt4 ghostscript libffi-dev cmake"
+  - "sudo apt-get -qq install libfreetype6-dev liblcms2-dev python-qt4 ghostscript libffi-dev cmake imagemagick"
   - "pip install cffi"
   - "pip install coveralls nose pyroma nose-cov"
   - if [ "$TRAVIS_PYTHON_VERSION" == "2.6" ]; then pip install unittest2; fi

Tests/helper.py

@@ -131,6 +131,17 @@ class PillowTestCase(unittest.TestCase):
         self.addCleanup(self.delete_tempfile, path)      
         return path
 
+    def open_withImagemagick(self, f):
+        if not imagemagick_available():
+            raise IOError()
+
+        outfile = self.tempfile("temp.png")
+        if command_succeeds(['convert', f, outfile]):
+            from PIL import Image
+            return Image.open(outfile)
+        raise IOError()
+    
+        
 # helpers
 
 import sys
@@ -194,4 +205,7 @@ def netpbm_available():
     return command_succeeds(["ppmquant", "--help"]) and \
            command_succeeds(["ppmtogif", "--help"])
 
+def imagemagick_available():
+    return command_succeeds(['convert', '-version'])
+                            
 # End of file

Tests/test_file_palm.py

@@ -1,10 +1,11 @@
-from helper import unittest, PillowTestCase, tearDownModule, lena
+from helper import unittest, PillowTestCase, tearDownModule, lena, imagemagick_available
 
 import os.path
 
 
 class TestFilePalm(PillowTestCase):
-
+    _roundtrip = imagemagick_available()
+    
     def helper_save_as_palm(self, mode):
         # Arrange
         im = lena(mode)
@@ -17,12 +18,25 @@ class TestFilePalm(PillowTestCase):
         self.assertTrue(os.path.isfile(outfile))
         self.assertGreater(os.path.getsize(outfile), 0)
 
+    def roundtrip(self, mode):
+        if not self._roundtrip:
+            return
+        
+        im = lena(mode)
+        outfile = self.tempfile("temp.palm")
+
+        im.save(outfile)
+        converted = self.open_withImagemagick(outfile)
+        self.assert_image_equal(converted, im)
+        
+
     def test_monochrome(self):
         # Arrange
         mode = "1"
 
         # Act / Assert
         self.helper_save_as_palm(mode)
+        self.roundtrip(mode)
 
     def test_p_mode(self):
         # Arrange
@@ -30,7 +44,8 @@ class TestFilePalm(PillowTestCase):
 
         # Act / Assert
         self.helper_save_as_palm(mode)
-
+        self.roundtrip(mode)
+        
     def test_rgb_ioerror(self):
         # Arrange
         mode = "RGB"