[chore, spec] Version: test 8-character hash just in case (#7809)

Cf. https://github.com/koreader/koreader/issues/7805#issuecomment-855337115.

spec/unit/version_spec.lua

@@ -17,7 +17,7 @@ describe("Version module", function()
         it("should get current version", function()
             assert.is_true(12 == tostring(Version:getNormalizedCurrentVersion()):len())
         end)
-        it("should get version", function()
+        it("should get version with 7-character hash", function()
             local rev = "v2015.11-982-g704d4238"
             local version, commit = Version:getNormalizedVersion(rev)
             local expected_version = 201511000982
@@ -25,6 +25,14 @@ describe("Version module", function()
             assert.are.same(expected_version, version)
             assert.are.same(expected_commit, commit)
         end)
+        it("should get version with 8-character hash", function()
+            local rev = "v2021.05-70-gae544b74"
+            local version, commit = Version:getNormalizedVersion(rev)
+            local expected_version = 202105000070
+            local expected_commit = "ae544b74"
+            assert.are.same(expected_version, version)
+            assert.are.same(expected_commit, commit)
+        end)
         it("should get version with four number revision", function()
             local rev = "v2015.11-1755-gecd7b5b_2018-07-02"
             local version, commit = Version:getNormalizedVersion(rev)