fix bbatsov#1806

projectile.el

@@ -3401,20 +3401,22 @@ a manual COMMAND-TYPE command is created with
 Normally you'd set this from .dir-locals.el.")
 (put 'projectile-project-type 'safe-local-variable #'symbolp)
 
-(defun projectile-detect-project-type ()
-  "Detect the type of the current project.
+(defun projectile-detect-project-type (&optional dir)
+  "Detect the type of the project.
+When DIR is specified it detect it, otherwise it acts on the current project.
 Fallsback to a generic project type when the type can't be determined."
   (let ((project-type
          (or (car (cl-find-if
                    (lambda (project-type-record)
-                     (let ((project-type (car project-type-record))
+                     (let ((default-directory (or dir default-directory))
+                           (project-type (car project-type-record))
                            (marker (plist-get (cdr project-type-record) 'marker-files)))
                        (if (functionp marker)
                            (and (funcall marker) project-type)
                          (and (projectile-verify-files marker) project-type))))
                    projectile-project-types))
              'generic)))
-    (puthash (projectile-project-root) project-type projectile-project-type-cache)
+    (puthash (projectile-project-root dir) project-type projectile-project-type-cache)
     project-type))
 
 (defun projectile-project-type (&optional dir)
@@ -3429,7 +3431,7 @@ The project type is cached for improved performance."
            (project-root (projectile-project-root dir)))
       (if project-root
           (or (gethash project-root projectile-project-type-cache)
-              (projectile-detect-project-type))
+              (projectile-detect-project-type dir))
         ;; if we're not in a project we just return nil
         nil))))