program: apply reduce only logic for post only orders (#1878)

* program: apply reduce only logic for post only orders

* CHANGELOG

Author: crispheaney

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Features
 
+- program: post only respects reduce only ([#1878](https://github.com/drift-labs/protocol-v2/pull/1878))
 - program: add sequence id to exchange/mm oracle ([#1834](https://github.com/drift-labs/protocol-v2/pull/1834))
 - program: perp position max margin ratio ([#1847](https://github.com/drift-labs/protocol-v2/pull/1847))
 - program: rm lp ([#1755](https://github.com/drift-labs/protocol-v2/pull/1755))

programs/drift/src/state/user.rs

@@ -1408,7 +1408,7 @@ impl Order {
         };
 
         // if order is post only, can disregard reduce only
-        if !self.reduce_only || self.post_only {
+        if !self.reduce_only {
             return Ok(base_asset_amount_unfilled);
         }