Fix credit in some of Ben Sheldon commits

The logic for false positives considers "/" to be a name connector, but some
commits from Ben Sheldon have "[he/him]" in the commit message. Current
heuristics guess that those commits have two authors:

    ["Ben Sheldon [he", "him]"]

This pattern needs a new rule.

app/models/names_manager/false_positives.rb

@@ -66,6 +66,10 @@ def handle_false_positives(name)
           $1
         when /\A(?:DHH\s*)?via\s+(.*)/i
           $1
+        # These are present in some of Ben Sheldon commits. This pattern needs
+        # ad-hoc handling because "/" is considered to be a name connector.
+        when %r{\[he/him\]}
+          $`.strip
         when /\b\w+\+\w+@/
           # The plus sign is taken to be a connector below, this catches some known
           # addresses that use a plus sign in the username, see unit tests for examples.

test/credits/false_positives_test.rb

@@ -269,5 +269,9 @@ class FalsePositivesTest < ActiveSupport::TestCase
     test 'ignores unknown contributors referred as "others"' do
       assert_contributor_names 'da4b15f', 'Kevin Jackson', 'David Heinemeier Hansson', exact: true
     end
+
+    test '[he/him] ad-hoc handling' do
+      assert_contributor_names 'fe03a19', 'Ben Sheldon'
+    end
   end
 end