http.manage: Do not prune expired certificates from ca table.

Because this is not the job of an import/export tool.

caucase/http.py

@@ -1114,7 +1114,7 @@ def manage(argv=None, stdout=sys.stdout):
     db = SQLite3Storage(db_path, table_prefix='cas')
     trusted_ca_crt_set = [
       utils.load_ca_certificate(x['crt_pem'])
-      for x in db.getCAKeyPairList()
+      for x in db.getCAKeyPairList(prune=False)
     ]
     latest_ca_not_after = max(
       x.not_valid_after
@@ -1159,7 +1159,7 @@ def manage(argv=None, stdout=sys.stdout):
       for key_pair in SQLite3Storage(
         db_path,
         table_prefix='cas',
-      ).getCAKeyPairList():
+      ).getCAKeyPairList(prune=False):
         write(
           key_pair['crt_pem'] + serialization.load_pem_private_key(
             key_pair['key_pem'],

caucase/storage.py

@@ -215,13 +215,14 @@ class SQLite3Storage(local):
     except sqlite3.IntegrityError:
       pass
 
-  def getCAKeyPairList(self):
+  def getCAKeyPairList(self, prune=True):
     """
     Return the chronologically sorted (oldest in [0], newest in [-1])
     certificate authority key pairs.
     """
     with self._db as db:
       c = db.cursor()
+      if prune:
         c.execute(
           'DELETE FROM %sca WHERE expiration_date < ?' % (
             self._table_prefix,