diff --git a/liberapay/billing/payday.py b/liberapay/billing/payday.py
index 65f7e8527..6e185bea3 100644
--- a/liberapay/billing/payday.py
+++ b/liberapay/billing/payday.py
@@ -539,7 +539,7 @@ def resolve_takes(tips, takes, ref_currency, payday_id):
         # members who have now left the team or have zeroed takes.
         transfers = list(transfers.values())
         leftover = total_income - MoneyBasket(t.amount for t in transfers)
-        assert leftover >= 0
+        assert leftover >= 0, "leftover is negative"
         if leftover and leftover_takes:
             leftover_takes.sort(key=lambda t: t.member)
             leftover_takes_fuzzy_sum = MoneyBasket(
diff --git a/liberapay/i18n/currencies.py b/liberapay/i18n/currencies.py
index 3bb355a46..a840f0a67 100644
--- a/liberapay/i18n/currencies.py
+++ b/liberapay/i18n/currencies.py
@@ -393,9 +393,9 @@ def __ne__(self, other):
 
     def _compare(self, op, other):
         if isinstance(other, self.__class__):
-            return self.amounts == other.amounts
+            return self.amounts.items() == other.amounts.items()
         elif other == 0:
-            return any(op(v, 0) for v in self.amounts.values())
+            return all(op(v, 0) for v in self.amounts.values())
         else:
             raise TypeError(
                 "can't compare %r and %r" % (self.__class__, other.__class__)
diff --git a/liberapay/utils/state_chain.py b/liberapay/utils/state_chain.py
index f7dc4b2e9..ca21d5c6e 100644
--- a/liberapay/utils/state_chain.py
+++ b/liberapay/utils/state_chain.py
@@ -1,7 +1,6 @@
-from urllib.parse import quote as urlquote, urlsplit, urlunsplit
+from urllib.parse import quote as urlquote
 
 from pando import Response
-from pando.http.request import Line
 import pando.state_chain
 from requests.exceptions import ConnectionError, Timeout
 
@@ -54,14 +53,6 @@ def canonize(request, response, website):
     """
     if request.path.raw.startswith('/callbacks/'):
         # Don't redirect callbacks
-        if request.path.raw[-1] == '/':
-            # Remove trailing slash
-            l = request.line
-            scheme, netloc, path, query, fragment = urlsplit(l.uri)
-            assert path[-1] == '/'  # sanity check
-            path = path[:-1]
-            new_uri = urlunsplit((scheme, netloc, path, query, fragment))
-            request.line = Line(l.method.raw, new_uri, l.version.raw)
         return
     canonical_host = website.canonical_host
     canonical_scheme = website.canonical_scheme