Update ledger *after* pps updates from new trades

Addressing same issue as in #350 where we need to compute position
updates using the *first read* from the ledger **before** we update it
to make sure `Position.lifo_update()` gets called and **not skipped**
because new trades were read as clears entries but haven't actually been
included in update calcs yet.. aka we call `Position.lifo_update()`.

Main change here is to convert `update_ledger()` into a context mngr so
that the ledger write is committed after pps updates using
`pp.update_pps_conf()`..

This is basically a hotfix to #346 as well.

piker/brokers/kraken/broker.py

@@ -18,7 +18,10 @@
 Order api and machinery
 
 '''
-from contextlib import asynccontextmanager as acm
+from contextlib import (
+    asynccontextmanager as acm,
+    contextmanager as cm,
+)
 from functools import partial
 from itertools import chain, count
 from pprint import pformat
@@ -260,13 +263,13 @@ async def trades_dialogue(
         log.info(
             f'Loaded {len(trades)} trades from account `{acc_name}`'
         )
-        trans = await update_ledger(acctid, trades)
-        active, closed = pp.update_pps_conf(
-            'kraken',
-            acctid,
-            trade_records=trans,
-            ledger_reload={}.fromkeys(t.bsuid for t in trans),
-        )
+        with open_ledger(acctid, trades) as trans:
+            active, closed = pp.update_pps_conf(
+                'kraken',
+                acctid,
+                trade_records=trans,
+                ledger_reload={}.fromkeys(t.bsuid for t in trans),
+            )
 
         position_msgs: list[dict] = []
         pps: dict[int, pp.Position]
@@ -426,14 +429,14 @@ async def handle_order_updates(
                     await ems_stream.send(filled_msg.dict())
 
                 # update ledger and position tracking
-                trans = await update_ledger(acctid, trades)
-                active, closed = pp.update_pps_conf(
-                    'kraken',
-                    acctid,
-                    trade_records=trans,
-                    ledger_reload={}.fromkeys(
-                        t.bsuid for t in trans),
-                )
+                with open_ledger(acctid, trades) as trans:
+                    active, closed = pp.update_pps_conf(
+                        'kraken',
+                        acctid,
+                        trade_records=trans,
+                        ledger_reload={}.fromkeys(
+                            t.bsuid for t in trans),
+                    )
 
                 # emit any new pp msgs to ems
                 for pos in filter(
@@ -743,7 +746,8 @@ def norm_trade_records(
     return records
 
 
-async def update_ledger(
+@cm
+def open_ledger(
     acctid: str,
     trade_entries: list[dict[str, Any]],
 
@@ -756,8 +760,10 @@ async def update_ledger(
         'kraken',
         acctid,
     ) as ledger:
-        ledger.update(trade_entries)
 
-    # normalize to transaction form
-    records = norm_trade_records(trade_entries)
-    return records
+        # normalize to transaction form
+        records = norm_trade_records(trade_entries)
+        yield records
+
+        # update on exit
+        ledger.update(trade_entries)