fixup! Extract extras from fragment's egg when vcs is specified

requirements/fragment.py

@@ -1,7 +1,12 @@
+import re
+
 # Copied from pip
 # https://github.com/pypa/pip/blob/281eb61b09d87765d7c2b92f6982b3fe76ccb0af/pip/index.py#L947
 HASH_ALGORITHMS = set(['sha1', 'sha224', 'sha384', 'sha256', 'sha512', 'md5'])
 
+extras_require_search = re.compile(
+    r'(?P<name>.+)\[(?P<extras>[^\]]+)\]').search
+
 
 def parse_fragment(fragment_string):
     """Takes a fragment string nd returns a dict of the components"""
@@ -30,7 +35,10 @@ def get_hash_info(d):
 
 
 def parse_extras_require(egg):
-    if egg is not None and ('[' and ']') in egg:
-        name, _, extras = egg.partition('[')
-        return name, [extra.strip() for extra in extras[:-1].split(',')]
+    if egg is not None:
+        match = extras_require_search(egg)
+        if match is not None:
+            name = match.group('name')
+            extras = match.group('extras')
+            return name, [extra.strip() for extra in extras.split(',')]
     return egg, []