Fix URL

`path.is_relative` return true for links like https://example.com.

So we have to check if the target of link and image
is a path to local file before we update them.

expected-auto.native

@@ -128,12 +128,29 @@
             ( "subdir/someimage.png" , "" )
         ]
     ]
+, Figure
+    ( "" , [] , [] )
+    (Caption
+       Nothing [ Plain [ Str "Image" , Space , Str "title" ] ])
+    [ Plain
+        [ Image
+            ( "" , [] , [] )
+            [ Str "Image" , Space , Str "title" ]
+            ( "https://example.com/someimage.png" , "" )
+        ]
+    ]
 , Para
     [ Link
         ( "" , [] , [] )
         [ Str "Some" , Space , Str "link" ]
         ( "subdir/someimage.png" , "" )
     ]
+, Para
+    [ Link
+        ( "" , [] , [] )
+        [ Str "Some" , Space , Str "link" ]
+        ( "https://example.com/someimage.png" , "" )
+    ]
 , Header
     2
     ( "source-include" , [] , [] )

expected.native

@@ -128,12 +128,29 @@
             ( "subdir/someimage.png" , "" )
         ]
     ]
+, Figure
+    ( "" , [] , [] )
+    (Caption
+       Nothing [ Plain [ Str "Image" , Space , Str "title" ] ])
+    [ Plain
+        [ Image
+            ( "" , [] , [] )
+            [ Str "Image" , Space , Str "title" ]
+            ( "https://example.com/someimage.png" , "" )
+        ]
+    ]
 , Para
     [ Link
         ( "" , [] , [] )
         [ Str "Some" , Space , Str "link" ]
         ( "subdir/someimage.png" , "" )
     ]
+, Para
+    [ Link
+        ( "" , [] , [] )
+        [ Str "Some" , Space , Str "link" ]
+        ( "https://example.com/someimage.png" , "" )
+    ]
 , Header
     1
     ( "source-include" , [] , [] )

include-files.lua

@@ -36,13 +36,19 @@ local function update_contents(blocks, shift_by, include_path)
     end,
     -- If link paths are relative then prepend include file path
     Link = function (link)
+        if string.match(link.target, "^%a+://") then
+          return link
+        end
         if path.is_relative(link.target) then
             link.target = path.normalize(path.join({include_path, link.target}))
         end
         return link
     end,
     -- If image paths are relative then prepend include file path
     Image = function (image)
+      if string.match(image.src, "^%a+://") then
+        return image
+      end
       if path.is_relative(image.src) then
         image.src = path.normalize(path.join({include_path, image.src}))
       end

subdir/file-g.md

@@ -4,8 +4,12 @@ Image relative path will be updated.
 
 ![Image title](someimage.png)
 
+![Image title](https://example.com/someimage.png)
+
 [Some link](someimage.png)
 
+[Some link](https://example.com/someimage.png)
+
 # Source include
 
 File inclusion codeblocks for use with include-code-files will be