Fix overeager Newick quoting

Includes regression test for #200

src/dendropy/dataio/newickwriter.py

@@ -378,7 +378,8 @@ def _render_node_tag(self, node):
         if tag:
             tag = nexusprocessing.escape_nexus_token(tag,
                     preserve_spaces=self.preserve_spaces,
-                    quote_underscores=not self.unquoted_underscores)
+                    quote_underscores=not self.unquoted_underscores,
+                    protect_regex=r'''[()[\],;:'"\0\t\n]''')
             return tag
         else:
             return ""

src/dendropy/dataio/nexusprocessing.py

@@ -470,17 +470,25 @@ def format_item_annotations_as_comments(
     body = separator.join(parts)
     return prefix + body + suffix
 
-def escape_nexus_token(label, preserve_spaces=False, quote_underscores=True):
+def escape_nexus_token(
+    label,
+    preserve_spaces=False,
+    quote_underscores=True,
+    protect_regex=r'''[()[\]{}\\\/,;:=*'"`+\-<>\0\t\n]''',
+):
     """
     Properly protects a NEXUS token.
+
+    Kwarg protect_regex allows less eager quoting when working with non-Nexus
+    Newick strings.
     """
     if label is None:
         return ""
     if not preserve_spaces \
             and "_" not in label \
-            and not re.search(r'''[()[\]{}\\\/,;:=*'"`+\-<>\0\t\n]''', label):
+            and not re.search(protect_regex, label):
         label = label.replace(' ', '_').replace('\t', '_')
-    elif re.search(r'''[()[\]{}\\\/,;:=*'"`+-<>\0\t\n\r ]''', label) \
+    elif re.search(protect_regex, label) \
         or quote_underscores and "_" in label:
         s = label.split("'")
         if len(s) == 1:

tests/unittests/test_dataio_newick_writer.py

@@ -143,6 +143,12 @@ def test_roundtrip_full(self):
             # is_coerce_metadata_values_to_string=True,
             # is_distinct_nodes_and_edges_representation=False)
 
+    def test_quoting_eagerness(self):
+        # regression test for #200
+        nw_str = "(A:0.36827875,B:0.186986942,(C:0.156890492,D:0.175861009)1.000:0.163375071);"
+        tree = dendropy.Tree.get(data=nw_str,schema="newick")
+        self.assertEqual(nw_str, tree.as_string("newick").strip())
+
 class NewickTreeWriterGeneralOptionsTests(
         compare_and_validate.ValidateWriteable,
         dendropytest.ExtendedTestCase):