After clearSearch nextSearchTerm is not cleared

https://github.com/ivaynberg/select2/issues/2753

select2.js

@@ -814,8 +814,6 @@ the specific language governing permissions and limitations under the Apache Lic
             // focusin can cause focus wars between modals and select2 since the dropdown is outside the modal.
             this.dropdown.on("click mouseup mousedown touchstart touchend focusin", function (e) { e.stopPropagation(); });
 
-            this.nextSearchTerm = undefined;
-
             if ($.isFunction(this.opts.initSelection)) {
                 // initialize selection based on the current value of the source element
                 this.initSelection();
@@ -1499,6 +1497,23 @@ the specific language governing permissions and limitations under the Apache Lic
 
         },
 
+        /**
+         * @private
+         */
+        prefillNextSearchTerm: function () {
+            // initializes search's value with nextSearchTerm (if defined by user)
+            // ignore nextSearchTerm if the dropdown is opened by the user pressing a letter
+            if(this.search.val() !== "") {
+                return;
+            }
+
+            var nextSearchTerm = this.opts.nextSearchTerm(this.data(), this.search.val());
+            if(nextSearchTerm != undefined){
+                this.search.val(nextSearchTerm);
+                this.search.select();
+            }
+        },
+
         //abstract
         getMaximumSelectionSize: function() {
             return evaluate(this.opts.maximumSelectionSize, this.opts.element);
@@ -2015,14 +2030,7 @@ the specific language governing permissions and limitations under the Apache Lic
                 }
             }
 
-            // initializes search's value with nextSearchTerm (if defined by user)
-            // ignore nextSearchTerm if the dropdown is opened by the user pressing a letter
-            if(this.search.val() === "") {
-                if(this.nextSearchTerm != undefined){
-                    this.search.val(this.nextSearchTerm);
-                    this.search.select();
-                }
-            }
+            this.prefillNextSearchTerm();
 
             this.focusser.prop("disabled", true).val("");
             this.updateResults(true);
@@ -2310,7 +2318,6 @@ the specific language governing permissions and limitations under the Apache Lic
                         self.updateSelection(selected);
                         self.close();
                         self.setPlaceholder();
-                        self.nextSearchTerm = self.opts.nextSearchTerm(selected, self.search.val());
                     }
                 });
             }
@@ -2447,7 +2454,6 @@ the specific language governing permissions and limitations under the Apache Lic
 
             this.opts.element.trigger({ type: "select2-selected", val: this.id(data), choice: data });
 
-            this.nextSearchTerm = this.opts.nextSearchTerm(data, this.search.val());
             this.close();
 
             if ((!options || !options.noFocus) && this.opts.shouldFocusInput(this)) {
@@ -2914,16 +2920,9 @@ the specific language governing permissions and limitations under the Apache Lic
 
             this.focusSearch();
 
-            // initializes search's value with nextSearchTerm (if defined by user)
-            // ignore nextSearchTerm if the dropdown is opened by the user pressing a letter
-            if(this.search.val() === "") {
-                if(this.nextSearchTerm != undefined){
-                    this.search.val(this.nextSearchTerm);
-                    this.search.select();
-                }
-            }
-
+            this.prefillNextSearchTerm();
             this.updateResults(true);
+
             if (this.opts.shouldFocusInput(this)) {
                 this.search.focus();
             }
@@ -2989,9 +2988,6 @@ the specific language governing permissions and limitations under the Apache Lic
 
             this.opts.element.trigger({ type: "selected", val: this.id(data), choice: data });
 
-            // keep track of the search's value before it gets cleared
-            this.nextSearchTerm = this.opts.nextSearchTerm(data, this.search.val());
-
             this.clearSearch();
             this.updateResults();
 
@@ -3010,11 +3006,8 @@ the specific language governing permissions and limitations under the Apache Lic
                         this.updateResults(true);
                     } else {
                         // initializes search's value with nextSearchTerm and update search result
-                        if(this.nextSearchTerm != undefined){
-                            this.search.val(this.nextSearchTerm);
-                            this.updateResults();
-                            this.search.select();
-                        }
+                        this.prefillNextSearchTerm();
+                        this.updateResults();
                     }
                     this.positionDropdown();
                 } else {