Use a raw string in :dir handling code for Python source blocks

Author: nnicandro

jupyter-python.el

@@ -99,7 +99,7 @@ import os
 __JUPY_saved_dir = os.getcwd()
 os.chdir(\"%s\")
 try:
-    get_ipython().run_cell(\"\"\"%s\"\"\")
+    get_ipython().run_cell(r\"\"\"%s\"\"\")
 finally:
     os.chdir(__JUPY_saved_dir)"
                   (plist-get changelist :dir) code)))

test/jupyter-test.el

@@ -2857,7 +2857,12 @@ os.path.abspath(os.getcwd())"
          (concat ": "
                  (funcall convert-path
                           (expand-file-name
-                           (directory-file-name default-directory))) "\n"))))))
+                           (directory-file-name default-directory))) "\n")))
+      (ert-info ("Transformed code and backslashes")
+        ;; See #302
+        (jupyter-org-test-src-block
+         "print(r\"\\r\")"
+         ": \\r\n")))))
 
 (ert-deftest jupyter-org--find-mime-types ()
   :tags '(org mime)