Version is incremented twice if the base version commit also has an explicit semver message

[MikeEvansLarah]

Test to repro:

[Test]
    public void CanUseCommitMessagesToBumpVersionBaseVersionTagIsAppliedToSameCommit()
    {
        using (var fixture = new EmptyRepositoryFixture())
        {
            fixture.Repository.MakeACommit();
            fixture.MakeATaggedCommit("1.0.0");
            fixture.Repository.MakeACommit("+semver:minor");
            fixture.AssertFullSemver("1.1.0+1");

            fixture.ApplyTag("2.0.0");

            fixture.Repository.MakeACommit("Hello");

            // Default bump is patch

            fixture.AssertFullSemver("2.0.1+1");
        }
    }

[pascalberger]

Fix available in #972