fix corner case in conditionals (#5548)

lib/ast.js

@@ -1428,8 +1428,10 @@ var AST_Import = DEFNODE("Import", "all default path properties quote", {
     },
     _equals: function(node) {
         return this.path == node.path
+            && prop_equals(this.all, node.all)
             && prop_equals(this.default, node.default)
-            && (this.all ? prop_equals(this.all, node.all) : all_equals(this.properties, node.properties));
+            && !this.properties == !node.properties
+            && (!this.properties || all_equals(this.properties, node.properties));
     },
     walk: function(visitor) {
         var node = this;

test/compress/imports.js

@@ -193,6 +193,22 @@ forbid_merge: {
     }
 }
 
+merge_tail: {
+    options = {
+        conditionals: true,
+    }
+    input: {
+        if (console)
+            import "foo";
+        else
+            import "foo";
+    }
+    expect: {
+        console;
+        import "foo";
+    }
+}
+
 issue_4708_1: {
     options = {
         imports: true,