Fix failing lsp-python-ms setup

Configuring lsp-python-ms variables properly.

CHANGELOG.develop

@@ -2196,6 +2196,7 @@ Other:
 - Made python-send-shell-* functions faster (thanks to Trapez Breen)
 - Added support for 'black' formatter (thanks to Mike Macpherson)
 - Enabled =eldoc= for =anaconda-mode= (thanks to Vikash Balasubramanian)
+- Various fixes for =lsp-python-ms= setup (thanks to Trapez Breen)
 **** Racket
 - Restore smart closing paren behavior in racket-mode (thanks to Don March)
 **** Ranger

layers/+lang/python/packages.el

@@ -428,12 +428,14 @@ fix this issue."
     :if (eq python-lsp-server 'mspyls)
     :ensure nil
     :config
-
-    (if python-lsp-git-root
+    (when python-lsp-git-root
       ;; Use dev version of language server checked out from github
-      (progn
-        (setq lsp-python-ms-dir
-          (expand-file-name (concat python-lsp-git-root "/output/bin/Release/")))
-        (message "lsp-python-ms: Using version at `%s'" lsp-python-ms-dir))
+      (setq lsp-python-ms-dir
+            (expand-file-name (concat python-lsp-git-root
+                                      "/output/bin/Release/")))
+      (message "lsp-python-ms: Using version at `%s'" lsp-python-ms-dir)
       ;; Use a precompiled exe
-      (setq lsp-python-ms-executable "Microsoft.Python.LanguageServer"))))
+      (setq lsp-python-ms-executable (concat lsp-python-ms-dir
+                                             "Microsoft.Python.LanguageServer"
+                                             (and (eq system-type 'windows-nt)
+                                                  ".exe"))))))