Automatically reconnect after fork regardless of reconnect_attempts

When an inherited connection is detected, we used to raise a BaseConnectionError
so an automatic reconnection would happen if `reconnect_attempts > 0`.

But it makes more sense to just reconnect, as it's not really an error case.

CHANGELOG.md

@@ -1,5 +1,7 @@
 # Unreleased
 
+* Automatically reconnect after fork regardless of `reconnect_attempts`
+
 # 4.8.0
 
 * Introduce `sadd?` and `srem?` as boolean returning versions of `sadd` and `srem`.

lib/redis/client.rb

@@ -399,23 +399,14 @@ def establish_connection
     end
 
     def ensure_connected
-      disconnect if @pending_reads > 0
+      disconnect if @pending_reads > 0 || (@pid != Process.pid && !inherit_socket?)
 
       attempts = 0
 
       begin
         attempts += 1
 
-        if connected?
-          unless inherit_socket? || Process.pid == @pid
-            raise InheritedError,
-                  "Tried to use a connection from a child process without reconnecting. " \
-                  "You need to reconnect to Redis after forking " \
-                  "or set :inherit_socket to true."
-          end
-        else
-          connect
-        end
+        connect unless connected?
 
         yield
       rescue BaseConnectionError

test/redis/fork_safety_test.rb

@@ -8,26 +8,18 @@ class TestForkSafety < Minitest::Test
   driver(:ruby, :hiredis) do
     def test_fork_safety
       redis = Redis.new(OPTIONS)
-      redis.set "foo", 1
+      assert_equal "PONG", @redis.ping
 
-      child_pid = fork do
-        begin
-          # InheritedError triggers a reconnect,
-          # so we need to disable reconnects to force
-          # the exception bubble up
-          redis.without_reconnect do
-            redis.set "foo", 2
-          end
-          exit! 0
-        rescue Redis::InheritedError
-          exit! 127
+      pid = fork do
+        1000.times do
+          assert_equal "OK", @redis.set("key", "foo")
         end
       end
-
-      _, status = Process.wait2(child_pid)
-
-      assert_equal 127, status.exitstatus
-      assert_equal "1", redis.get("foo")
+      1000.times do
+        assert_equal "PONG", @redis.ping
+      end
+      _, status = Process.wait2(pid)
+      assert_predicate(status, :success?)
     rescue NotImplementedError => error
       raise unless error.message =~ /fork is not available/
     end