Correctly handle template change

When user decides to change eg. source language, we can not mark all
strings fuzzy.

On the other side this is quite corner case, so it does not matter that
it's handling is not optimal, but rather the fuzzy flag is removed
later.

Fixes #991
Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/models/subproject.py

@@ -1017,7 +1017,8 @@ class SubProject(models.Model, PercentMixin, URLMixin, PathMixin):
                 matches.discard(filename)
         return sorted(matches)
 
-    def create_translations(self, force=False, langs=None, request=None):
+    def create_translations(self, force=False, langs=None, request=None,
+                            changed_template=False):
         '''
         Loads translations from VCS.
         '''
@@ -1051,6 +1052,9 @@ class SubProject(models.Model, PercentMixin, URLMixin, PathMixin):
                 )
                 translations.add(translation.id)
                 languages.add(lang.code)
+                # Remove fuzzy flag on template name change
+                if changed_template:
+                    translation.unit_set.update(fuzzy=False)
 
         # Delete possibly no longer existing translations
         if langs is None:
@@ -1366,6 +1370,7 @@ class SubProject(models.Model, PercentMixin, URLMixin, PathMixin):
         # Detect if VCS config has changed (so that we have to pull the repo)
         changed_git = True
         changed_setup = False
+        changed_template = False
         changed_project = False
         if self.id:
             old = SubProject.objects.get(pk=self.id)
@@ -1379,6 +1384,10 @@ class SubProject(models.Model, PercentMixin, URLMixin, PathMixin):
                 (old.edit_template != self.edit_template) or
                 (old.template != self.template)
             )
+            changed_template = (
+                (old.edit_template != self.edit_template) and
+                self.template
+            )
             changed_project = (old.project_id != self.project_id)
             # Detect slug changes and rename git repo
             self.check_rename(old)
@@ -1401,7 +1410,10 @@ class SubProject(models.Model, PercentMixin, URLMixin, PathMixin):
         # Rescan for possibly new translations if there were changes, needs to
         # be done after actual creating the object above
         if changed_setup:
-            self.create_translations(force=True)
+            self.create_translations(
+                force=True,
+                changed_template=changed_template
+            )
         elif changed_git:
             self.create_translations()