[Bug]: history migration not working

[kordano]

What version of Datahike are you using?

0.4.1480

What version of Java are you using?

openjdk version "11.0.13" 2021-10-19

What operating system are you using?

Ubuntu 20.04.3 LTS

What database EDN configuration are you using?

{:store              {:backend :mem
                      :id      "export"}
 :keep-history?      true
 :schema-flexibility :write
 :attribute-refs?    false}

Describe the bug

When exporting a database with historical data and importing it into a new database, the historical data like removal and original data are lost.

What is the expected behaviour?

History should be imported as well.

How can the behaviour be reproduced?

(require '[datahike.api :as d])
(require '[datahike.migrate :as m])

(def schema [{:db/ident       :name
              :db/cardinality :db.cardinality/one
              :db/index       true
              :db/unique      :db.unique/identity
              :db/valueType   :db.type/string}
             {:db/ident       :parents
              :db/cardinality :db.cardinality/many
              :db/valueType   :db.type/ref}
             {:db/ident       :age
              :db/cardinality :db.cardinality/one
              :db/valueType   :db.type/long}])

(def export-cfg {:store              {:backend :mem
                                      :id      "export"}
                 :keep-history?      true
                 :schema-flexibility :write
                 :attribute-refs?    false})

(do
  (d/delete-database export-cfg)
  (d/create-database export-cfg))

(def export-conn (d/connect export-cfg))

(d/transact export-conn schema)

(d/transact export-conn {:tx-data [{:name "Alice" :age  25}
                                   {:name "Bob" :age  35}]})

(d/transact export-conn {:tx-data [{:name    "Charlie"
                                    :age     5
                                    :parents [[:name "Alice"] [:name "Bob"]]}]})

(d/transact export-conn {:tx-data [{:name "Daisy" :age 20}]})
(d/transact export-conn {:tx-data [{:name "Erhard" :age 20}]})

(d/transact export-conn {:tx-data [[:db/retractEntity [:name "Erhard"]]]})

(datahike.migrate/export-db @export-conn "/tmp/dh.dump")

(def import-cfg {:store              {:backend :mem
                               :id      "import"}
          :keep-history?      true
          :schema-flexibility :write
          :attribute-refs?    false})

(do
  (d/delete-database import-cfg)
  (d/create-database import-cfg))

(def import-conn (d/connect import-cfg))

(datahike.migrate/import-db import-conn "/tmp/dh.dump")

(= (d/datoms (d/history @export-conn) :eavt)
   (d/datoms (d/history @import-conn) :eavt))
;; => false