Do not store change object for not yet saved subproject

Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/models/subproject.py

@@ -828,6 +828,7 @@ class SubProject(models.Model, PercentMixin, URLMixin, PathMixin):
                     '%s remote into repo',
                     self.merge_style,
                 )
+                if self.id:
                     Change.objects.create(
                         subproject=self,
                         user=request.user if request else None,
@@ -849,6 +850,7 @@ class SubProject(models.Model, PercentMixin, URLMixin, PathMixin):
                 # Reset repo back
                 method(abort=True)
 
+        if self.id:
             Change.objects.create(
                 subproject=self,
                 user=request.user if request else None,