revlog: synchronise the various attribute holding the index filename

The segmentfile and the attribute need to be synchronized, let's enforce that.

mercurial/revlog.py

@@ -358,7 +358,7 b' class _InnerRevlog:'
         self.opener = opener
         self.index = index
 
-        self.index_file = index_file
+        self.__index_file = index_file
         self.data_file = data_file
         self.sidedata_file = sidedata_file
         self.inline = inline
@@ -381,6 +381,16 b' class _InnerRevlog:'
             self.data_config.chunk_cache_size,
         )
 
+    @property
+    def index_file(self):
+        return self.__index_file
+
+    @index_file.setter
+    def index_file(self, new_index_file):
+        self.__index_file = new_index_file
+        if self.inline:
+            self._segmentfile.filename = new_index_file
+
     # Derived from index values.
 
     def start(self, rev):