[FIX] web: do not change pager when discarding changes

Here is a scenario that could happen before this commit:
1. go to a list view with more than one record, say 3
2. click on the 3rd record to open the form view
3. the pager says 3/3
4. click on edit button
5. click on discard button
6. the pager says 1/3 (but the record displayed is still the same)

It is often necessary to restore the offset for the sub records, because
the number of pages in a one2many could have changed.  However, it is
not a good idea to do that for the main record, since it interferes with
the usual flow of operations.

1 files changed, 2 insertions, 0 deletions

diff --git a/addons/web/static/src/js/views/basic/basic_model.js b/addons/web/static/src/js/views/basic/basic_model.js
index 8fdcb305ddc..969e81576b1 100644
--- a/addons/web/static/src/js/views/basic/basic_model.js
+++ b/addons/web/static/src/js/views/basic/basic_model.js
@@ -347,6 +347,7 @@ var BasicModel = AbstractModel.extend({
         var element = this.localData[id];
         var isNew = this.isNew(id);
         var rollback = 'rollback' in options ? options.rollback : isNew;
+        var initialOffset = element.offset;
         this._visitChildren(element, function (elem) {
             if (rollback && elem._savePoint) {
                 if (elem._savePoint instanceof Array) {
@@ -365,6 +366,7 @@ var BasicModel = AbstractModel.extend({
                 delete elem.tempLimitIncrement;
             }
         });
+        element.offset = initialOffset;
     },
     /**
      * Duplicate a record (by calling the 'copy' route)