Added detection for edge case that could happen with existing records where the value is '@'

TransIP allows '@' as value to alias the root record.
'@' was on populate appended with the zone, which trigger an unneeded update.
'@' => '@.example.com.' -> 'example.com'
This fix will stop the unneeded update

octodns/provider/transip.py

@@ -218,7 +218,12 @@ class TransipProvider(BaseProvider):
 
     def _parse_to_fqdn(self, value):
 
-        if (value[-1] != '.'):
+        # TransIP allows '@' as value to alias the root record.
+        # this provider won't set an '@' value, but can be an existing record
+        if value == self.ROOT_RECORD:
+            value = self._currentZone.name
+
+        if value[-1] != '.':
             self.log.debug('parseToFQDN: changed %s to %s', value,
                            '{}.{}'.format(value, self._currentZone.name))
             value = '{}.{}'.format(value, self._currentZone.name)

tests/test_octodns_provider_transip.py

@@ -188,6 +188,8 @@ N4OiVz1I3rbZGYa396lpxO6ku8yCglisL1yrSP6DdEUp66ntpKVd
                           provider._parse_to_fqdn("www.unit.tests."))
         self.assertEquals("www.sub.sub.sub.unit.tests.",
                           provider._parse_to_fqdn("www.sub.sub.sub"))
+        self.assertEquals("unit.tests.",
+                          provider._parse_to_fqdn("@"))
 
         # Happy Plan - Even if the zone has no records the zone should exist
         provider = TransipProvider('test', 'unittest', self.bogus_key)