fix(gui): Crash comparing backups using diff feature

Bug was introduced with 5506854 and released in 1.5.5 and 1.5.6.

---------

Co-authored-by: Christian Buhtz <c.buhtz@posteo.jp>

Author: madic-creates

CHANGES

@@ -51,6 +51,7 @@ Version 1.6.0-dev (development of upcoming release)
 * Removed: UI translation in Bosnian, Thai, and Occidental/Interlingue (#1914)
 * Removed: LICENSE file in favor of LICENSES directory and LICENSES.md file
 * Removed: SSH Cipher configuration in Manage profiles dialog (#2143)
+* Fixed: Crash in Compare snapshots dialog (aka Snapshots dialog) whhen comparing/diff two backups (#2327 Michael Neese @madic-creates)
 * Fixed: Enforce UTF-8 encoding in takesnapshot.log and some other files (#2298)
 * Fixed: Attribute error about missing 'cbCopyUnsafeLinks' (#2279)
 * Fixed: Use LC_ALL instead of LC_TIME to set the locale

qt/snapshotsdialog.py

@@ -373,7 +373,7 @@ def timeLineExecute(self, _item, _column):
         # prevent backup data from being accidentally overwritten
         # by create a temporary local copy and only open that one
         if not isinstance(self.sid, snapshots.RootSnapshot):
-            full_path = self.parent.tmpCopy(full_path, sid)
+            full_path = self.parent._create_temporary_copy(full_path, sid)
 
         QDesktopServices.openUrl(QUrl(full_path))
 
@@ -400,9 +400,9 @@ def btnDiffClicked(self):
         # prevent backup data from being accidentally overwritten
         # by create a temporary local copy and only open that one
         if not isinstance(sid1, snapshots.RootSnapshot):
-            path1 = self.parent.tmpCopy(path1, sid1)
+            path1 = self.parent._create_temporary_copy(path1, sid1)
         if not isinstance(sid2, snapshots.RootSnapshot):
-            path2 = self.parent.tmpCopy(path2, sid2)
+            path2 = self.parent._create_temporary_copy(path2, sid2)
 
         params = diffParams
         params = params.replace('%1', '"%s"' % path1)