Fix GH-10315: FPM unknown child alert not valid

This changes the log level for an unknown child during wait as this is
not unuasual if FPM master has pid 1 and also possible in some cases
for higher pid processes. Based on that and the fact that this is not
really a problem, there is just a debug level message emitted for pid 1
and for higher pid a warning is emitted.

Closes GH-10319

Author: bukka

NEWS

@@ -17,6 +17,9 @@ PHP                                                                        NEWS
 - FFI:
   . Fixed incorrect bitshifting and masking in ffi bitfield. (nielsdos)
 
+- FPM:
+  . Fixed bug GH-10315 (FPM unknown child alert not valid). (Jakub Zelenka)
+
 - Opcache:
   . Fix incorrect page_size check. (nielsdos)
 

sapi/fpm/fpm/fpm_children.c

@@ -297,8 +297,10 @@ void fpm_children_bury(void)
 					break;
 				}
 			}
+		} else if (fpm_globals.parent_pid == 1) {
+			zlog(ZLOG_DEBUG, "unknown child (%d) exited %s - most likely an orphan process (master process is the init process)", pid, buf);
 		} else {
-			zlog(ZLOG_ALERT, "oops, unknown child (%d) exited %s. Please open a bug report (https://github.com/php/php-src/issues).", pid, buf);
+			zlog(ZLOG_WARNING, "unknown child (%d) exited %s - potentially a bug or pre exec child (e.g. s6-notifyoncheck)", pid, buf);
 		}
 	}
 }