chore: remove decrease revert

.github/workflows/lint.yaml

@@ -28,10 +28,10 @@ jobs:
         with:
           fetch-depth: 1
 
-      - name: Set up python 3.8
+      - name: Set up python 3.9
         uses: actions/setup-python@v2
         with:
-          python-version: 3.10
+          python-version: 3.9
 
       - name: Set pip cache directory path
         id: pip-cache-dir-path

contracts/VaultV3.vy

@@ -1061,12 +1061,14 @@ def _update_debt(strategy: address, target_debt: uint256, max_loss: uint256) ->
         withdrawable: uint256 = IStrategy(strategy).convertToAssets(
             IStrategy(strategy).maxRedeem(self)
         )
-        assert withdrawable != 0, "nothing to withdraw"
 
         # If insufficient withdrawable, withdraw what we can.
         if withdrawable < assets_to_withdraw:
             assets_to_withdraw = withdrawable
 
+        if assets_to_withdraw == 0:
+            return current_debt
+
         # If there are unrealised losses we don't let the vault reduce its debt until there is a new report
         unrealised_losses_share: uint256 = self._assess_share_of_unrealised_losses(strategy, assets_to_withdraw)
         assert unrealised_losses_share == 0, "strategy has unrealised losses"
@@ -1101,7 +1103,7 @@ def _update_debt(strategy: address, target_debt: uint256, max_loss: uint256) ->
     else: 
         # We are increasing the strategies debt
 
-        # Respect the maximum amount allowed. TODO: Should this just check if max uint?
+        # Respect the maximum amount allowed.
         max_debt: uint256 = self.strategies[strategy].max_debt
         if new_debt > max_debt:
             new_debt = max_debt

tests/unit/vault/test_debt_management.py

@@ -96,7 +96,7 @@ def test_update_debt__with_current_debt_equal_to_new_debt__reverts(
         vault.update_debt(strategy.address, new_debt, sender=gov)
 
 
-def test_update_debt__with_current_debt_greater_than_new_debt_and_zero_withdrawable__reverts(
+def test_update_debt__with_current_debt_greater_than_new_debt_and_zero_withdrawable(
     gov, asset, vault, locked_strategy, add_debt_to_strategy
 ):
     vault_balance = asset.balanceOf(vault)
@@ -109,8 +109,9 @@ def test_update_debt__with_current_debt_greater_than_new_debt_and_zero_withdrawa
     # reduce debt in strategy
     vault.update_max_debt_for_strategy(locked_strategy.address, new_debt, sender=gov)
 
-    with ape.reverts("nothing to withdraw"):
-        vault.update_debt(locked_strategy.address, new_debt, sender=gov)
+    tx = vault.update_debt(locked_strategy.address, new_debt, sender=gov)
+
+    assert tx.return_value == current_debt
 
 
 def test_update_debt__with_current_debt_greater_than_new_debt_and_strategy_has_losses__reverts(