Restore cached user name on transaction rollback

Zotero.Users.setName() updated the in-memory cache even if the
transaction was later rolled back, so a retry (e.g., of a failed sync
download batch) would skip rewriting the users row.

chrome/content/zotero/xpcom/users.js

@@ -139,6 +139,18 @@ Zotero.Users = new function () {
 			return;
 		}
 		await Zotero.DB.queryAsync("REPLACE INTO users VALUES (?, ?)", [userID, name]);
+		// Restore the cached name if the transaction is rolled back
+		if (Zotero.DB.inTransaction()) {
+			let previous = _users[userID];
+			Zotero.DB.addCurrentCallback("rollback", () => {
+				if (previous === undefined) {
+					delete _users[userID];
+				}
+				else {
+					_users[userID] = previous;
+				}
+			});
+		}
 		_users[userID] = name;
 	}
 };

test/tests/usersTest.js

@@ -0,0 +1,20 @@
+describe("Zotero.Users", function () {
+	describe("#setName()", function () {
+		it("should restore the cached name if the transaction is rolled back", async function () {
+			var userID = 24631244;
+			await Zotero.Users.setName(userID, 'A');
+			await executeTransactionWithForcedRollback(async function () {
+				await Zotero.Users.setName(userID, 'B');
+				assert.equal(Zotero.Users.getName(userID), 'B');
+			});
+			assert.equal(Zotero.Users.getName(userID), 'A');
+			
+			// A later save should write the new name to the database
+			await Zotero.Users.setName(userID, 'B');
+			assert.equal(
+				await Zotero.DB.valueQueryAsync("SELECT name FROM users WHERE userID=?", userID),
+				'B'
+			);
+		});
+	});
+});