diff -r 88472e743c64 -r 079dbf36e884 hgext3rd/evolve/stablerangecache.py
--- a/hgext3rd/evolve/stablerangecache.py	Tue Aug 06 11:17:38 2019 +0200
+++ b/hgext3rd/evolve/stablerangecache.py	Tue Aug 06 11:26:29 2019 +0200
@@ -223,7 +223,7 @@
             except (sqlite3.DatabaseError, sqlite3.OperationalError):
                 # something is wrong with the sqlite db
                 # Since this is a cache, we ignore it.
-                if '_con' in vars(self):
+                if r'_con' in vars(self):
                     del self._con
                 self._unsavedsubranges.clear()
 
@@ -278,7 +278,7 @@
             #
             # operational error catch read-only and locked database
             # IntegrityError catch Unique constraint error that may arise
-            if '_con' in vars(self):
+            if r'_con' in vars(self):
                 del self._con
             self._unsavedsubranges.clear()
             repo.ui.log('evoext-cache', 'error while saving new data: %s' % exc)
@@ -294,7 +294,7 @@
 
         if self._con is None:
             util.unlinkpath(self._path, ignoremissing=True)
-            if '_con' in vars(self):
+            if r'_con' in vars(self):
                 del self._con
 
             con = self._db()
@@ -375,7 +375,7 @@
 
     def clear(self, reset=False):
         super(stablerangesql, self).clear(reset=reset)
-        if '_con' in vars(self):
+        if r'_con' in vars(self):
             del self._con
         self._subrangescache.clear()
 
@@ -436,7 +436,7 @@
 
         @localrepo.unfilteredmethod
         def destroyed(self):
-            if 'stablerange' in vars(self):
+            if r'stablerange' in vars(self):
                 self.stablerange.clear()
                 del self.stablerange
             super(stablerangerepo, self).destroyed()