Make new test pass

This commit makes Proxy.git_describe_commit pass the passed-in value of OnlyFollowFirstParent through to NativeMethods.git_describe_commit, causing the test created in the previous commit to pass.

Author: ninjeff

LibGit2Sharp/Core/Proxy.cs

@@ -644,7 +644,7 @@ public static string git_describe_commit(
                     Version = 1,
                     DescribeStrategy = options.Strategy,
                     MaxCandidatesTags = 10,
-                    OnlyFollowFirstParent = false,
+                    OnlyFollowFirstParent = options.OnlyFollowFirstParent,
                     ShowCommitOidAsFallback = options.UseCommitIdAsFallback,
                 };