Fixed pxe install archive md5 file

The md5 sum must be created from the uncompressed version
of the disk image

kiwi/builder/install.py

@@ -280,7 +280,7 @@ class InstallImageBuilder(object):
                 self.xml_state.xml_data.get_name(), '.md5'
             ]
         )
-        checksum = Checksum(pxe_image_filename)
+        checksum = Checksum(self.diskname)
         checksum.md5(pxe_md5_filename)
 
         # the kiwi initrd code triggers the install by trigger files

test/unit/builder_install_test.py

@@ -255,7 +255,7 @@ class TestInstallImageBuilder(object):
             ['mv', compress.compressed_filename, 'tmpdir/result-image.xz']
         )
         mock_md5.assert_called_once_with(
-            'tmpdir/result-image.xz'
+            'target_dir/result-image.x86_64-1.2.3.raw'
         )
         checksum.md5.assert_called_once_with(
             'tmpdir/result-image.md5'