Add `common.is_absolute_path`

data/core/common.lua

@@ -385,6 +385,11 @@ function common.normalize_path(filename)
 end
 
 
+function common.is_absolute_path(path)
+  return path:sub(1, 1) == PATHSEP or path:match("^(%a):\\")
+end
+
+
 function common.path_belongs_to(filename, path)
   return string.find(filename, path .. PATHSEP, 1, true) == 1
 end

data/core/init.lua

@@ -605,7 +605,7 @@ end
 -- This function should get only filenames normalized using
 -- common.normalize_path function.
 function core.project_absolute_path(filename)
-  if filename:match('^%a:\\') or filename:find('/', 1, true) == 1 then
+  if common.is_absolute_path(filename) then
     return common.normalize_path(filename)
   elseif not core.project_dir then
     local cwd = system.absolute_path(".")