CI: fix tdsharp updater

There were two issues with the existing code:
1. isDescendant function was incorrectly called: the potentialAscendant and potentialDescendant arguments were mixed up. The first argument is supposed to be older (it's what the function checks).
2. The fetchGitSubmodule function wasn't only fetching it, but also updating it to the latest commit.

As the result, it all lead to a paradoxical situation when the Git submodule only gets updated if the last tagged commit in tdsharp is an ancestor of the last commit in tdsharp — meaning the updates happened on any new commits after a tdsharp release.

Author: ForNeVeR

update-tdsharp.fsx

@@ -37,16 +37,16 @@ let processCommandResult(result: CommandResult, assertSuccess: bool) =
 
 let assertCommandResult result = processCommandResult(result, true)
 
-let isDescendant potentialDescendant potentialAscendant =
-    if potentialDescendant = potentialAscendant then false
+let isAncestor (potentialAncestor: string) (potentialDescendant: string) =
+    if potentialAncestor = potentialDescendant then false
     else
 
     let commandResult =
         Command.Run(
             "git",
             arguments = [|
                 "merge-base";
-                "--is-ancestor"; potentialAscendant; potentialDescendant
+                "--is-ancestor"; potentialAncestor; potentialDescendant
             |],
             options = fun opts -> opts.WorkingDirectory tdSharpSources.Value |> ignore
         ).Result
@@ -76,17 +76,18 @@ let readLatestVersion() = task {
 }
 
 let fetchGitSubmodule() =
-    printfn "Fetching the Git sources…"
+    printfn "Initializing the Git submodule…"
     Command.Run(
         "git",
-        "submodule", "update", "--init", "--remote", "--", tdSharpSources.Value
+        "submodule", "update", "--init", "--", tdSharpSources.Value
     ).Result |> assertCommandResult
+    printfn "Fetching the Git submodule…"
     Command.Run(
         "git",
         arguments = [| "fetch"; "--all" |],
         options = fun opts -> opts.WorkingDirectory tdSharpSources.Value |> ignore
     ).Result |> assertCommandResult
-    printfn "Git sources fetched."
+    printfn "Git submodule fetched."
 
 let updateGitSubmodule(commitHash: string) =
     printfn $"Checking out the Git submodule at commit {commitHash}…"
@@ -118,7 +119,7 @@ let latestCommit = latestTag.Commit.Sha
 
 let result =
     printfn $"Current commit: {currentCommit}, latest commit: {latestCommit}."
-    if isDescendant currentCommit latestCommit then
+    if isAncestor currentCommit latestCommit then
         printfn $"Updating to {latestTag.Name} ({latestCommit})…"
         Some <| updateTo latestTag
     else