FIX: Multiple bulk importer fixes (#37740)

script/bulk_import/base.rb

@@ -1329,6 +1329,8 @@ class BulkImport::Base
     end
 
     @users[user[:imported_id].to_i] = user[:id] = @last_user_id += 1
+    @emails[user[:email]] = user[:id] if user[:email].present?
+    @external_ids[user[:external_id]] = user[:id] if user[:external_id].present?
 
     imported_username = user[:original_username].presence || user[:username].dup
 
@@ -2246,8 +2248,7 @@ class BulkImport::Base
     name.gsub!(/[^A-Za-z0-9]+$/, "")
     name.gsub!(/([-_.]{2,})/) { $1.first }
     name.strip!
-    name.truncate(60)
-    name
+    name.truncate(60, omission: "")
   end
 
   def random_username
@@ -2362,7 +2363,14 @@ class BulkImport::Base
 
   def normalize_text(text)
     return nil if text.blank?
-    @html_entities.decode(normalize_charset(text.presence || "").scrub)
+    text = normalize_charset(text.presence || "").scrub
+    # Escape HTML-encoded UTF-16 surrogates (e.g. �) so they pass through
+    # as literal text instead of crashing the HTML entity decoder.
+    text.gsub!(/&#(x?)(\h+);/) do
+      cp = $1.empty? ? $2.to_i : $2.to_i(16)
+      (0xD800..0xDFFF).cover?(cp) ? "&##{$1}#{$2};" : $&
+    end
+    @html_entities.decode(text)
   end
 
   def normalize_charset(text)

script/bulk_import/generic_bulk.rb

@@ -602,7 +602,7 @@ class BulkImport::Generic < BulkImport::Base
 
     create_user_emails(users) do |row|
       user_id = user_id_from_imported_id(row["id"])
-      next if user_id && existing_user_ids.include?(user_id)
+      next unless user_id && existing_user_ids.add?(user_id)
 
       if row["anonymized"] == 1
         username = username_from_id(user_id)
@@ -628,7 +628,7 @@ class BulkImport::Generic < BulkImport::Base
 
     create_user_profiles(users) do |row|
       user_id = user_id_from_imported_id(row["id"])
-      next if user_id && existing_user_ids.include?(user_id)
+      next unless user_id && existing_user_ids.add?(user_id)
 
       if row["anonymized"] == 1
         row["bio"] = nil
@@ -659,7 +659,7 @@ class BulkImport::Generic < BulkImport::Base
 
     create_user_options(users) do |row|
       user_id = user_id_from_imported_id(row["id"])
-      next if user_id && existing_user_ids.include?(user_id)
+      next unless user_id && existing_user_ids.add?(user_id)
 
       {
         user_id: user_id,
@@ -755,7 +755,7 @@ class BulkImport::Generic < BulkImport::Base
 
     create_single_sign_on_records(users) do |row|
       user_id = user_id_from_imported_id(row["id"])
-      next if user_id && existing_user_ids.include?(user_id)
+      next unless user_id && existing_user_ids.add?(user_id)
 
       sso_record = JSON.parse(row["sso_record"], symbolize_names: true)
       sso_record[:user_id] = user_id
@@ -949,12 +949,15 @@ class BulkImport::Generic < BulkImport::Base
       SQL
 
       poll_details.each do |poll|
-        if (placeholder = poll_mapping[poll["id"]])
+        if (placeholder = poll_mapping.delete(poll["id"]))
           raw.gsub!(placeholder, poll_bbcode(poll))
         end
       end
 
       poll_details.close
+
+      # Remove placeholders for polls without options
+      poll_mapping.each_value { |placeholder| raw.gsub!(placeholder, "") }
     end
 
     if (mentions = placeholders&.fetch("mentions", nil))