When you drag a tab from the tabbar into a split pane, that causes removeTab:...

When you drag a tab from the tabbar into a split pane, that causes removeTab: to be called. It tries to create a restorable session to undo closure, but because no sessions actually get closed in this operation we create an empty shell of a restorable session. When it's restored, you get a zombie tab with no view. This commit ignores such operations and declines to push a restorable session on the stack. Issue 5785.

iTerm2.xcodeproj/project.pbxproj

@@ -7181,7 +7181,8 @@
 						DevelopmentTeam = H7V7XYVQ7D;
 					};
 					874206460564169600CFC3F1 = {
-						ProvisioningStyle = Manual;
+						DevelopmentTeam = H7V7XYVQ7D;
+						ProvisioningStyle = Automatic;
 					};
 					A66717851DCE36C3000CE608 = {
 						DevelopmentTeam = H7V7XYVQ7D;
@@ -8954,10 +8955,10 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CLANG_WARN_INT_CONVERSION = YES;
-				CODE_SIGN_IDENTITY = "Developer ID Application: GEORGE NACHMAN (H7V7XYVQ7D)";
+				CODE_SIGN_IDENTITY = "Mac Developer";
 				COMBINE_HIDPI_IMAGES = YES;
 				COPY_PHASE_STRIP = YES;
-				DEVELOPMENT_TEAM = "";
+				DEVELOPMENT_TEAM = H7V7XYVQ7D;
 				FRAMEWORK_SEARCH_PATHS = (
 					"$(inherited)",
 					"$(SRCROOT)",
@@ -10133,11 +10134,11 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CLANG_WARN_INT_CONVERSION = YES;
-				CODE_SIGN_IDENTITY = "Developer ID Application: GEORGE NACHMAN (H7V7XYVQ7D)";
+				CODE_SIGN_IDENTITY = "Mac Developer";
 				COMBINE_HIDPI_IMAGES = YES;
 				COPY_PHASE_STRIP = NO;
 				DEBUG_INFORMATION_FORMAT = dwarf;
-				DEVELOPMENT_TEAM = "";
+				DEVELOPMENT_TEAM = H7V7XYVQ7D;
 				FRAMEWORK_SEARCH_PATHS = (
 					"$(inherited)",
 					"$(SRCROOT)",
@@ -10203,10 +10204,10 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CLANG_WARN_INT_CONVERSION = YES;
-				CODE_SIGN_IDENTITY = "Developer ID Application: GEORGE NACHMAN (H7V7XYVQ7D)";
+				CODE_SIGN_IDENTITY = "Mac Developer";
 				COMBINE_HIDPI_IMAGES = YES;
 				COPY_PHASE_STRIP = YES;
-				DEVELOPMENT_TEAM = "";
+				DEVELOPMENT_TEAM = H7V7XYVQ7D;
 				FRAMEWORK_SEARCH_PATHS = (
 					"$(inherited)",
 					"$(SRCROOT)",

sources/iTermController.m

@@ -1327,7 +1327,9 @@ static iTermController *gSharedInstance;
     iTermRestorableSession *session = self.currentRestorableSession;
     assert(session);
     if (session) {
-        [_restorableSessions addObject:session];
+        if (session.sessions.count > 0) {
+            [_restorableSessions addObject:session];
+        }
         [_currentRestorableSessionsStack removeObjectAtIndex:0];
     }
 }