Fix #1513849 [Edit E-Book will not save after editing if original file is not in its directory.](https://bugs.launchpad.net/calibre/+bug/1513849)

src/calibre/gui2/tweak_book/save.py

@@ -34,6 +34,7 @@ def save_container(container, path):
     if hasattr(os, 'fchmod'):
         # Ensure file permissions and owner information is preserved
         fno = temp.fileno()
+        st = None
         try:
             st = os.stat(path)
         except EnvironmentError as err:
@@ -41,7 +42,13 @@ def save_container(container, path):
                 raise
             # path may not exist if we are saving a copy, in which case we use
             # the metadata from the original book
+            try:
                 st = os.stat(container.path_to_ebook)
+            except EnvironmentError as err:
+                if err.errno != errno.ENOENT:
+                    raise
+                # Somebody deleted the original file
+        if st is not None:
             try:
                 os.fchmod(fno, st.st_mode)
             except EnvironmentError as err: