Refs codership/mysql-wsrep#141: this commit

1. Passes wsrep_sst_auth_value to SST scripts via WSREP_SST_OPT_AUTH envronmental variable, so it never appears on the command line
  2. In mysqldump and xtrabackup* SST scripts which rely on MySQL authentication, instead of passing password on the command line, SST script sets MYSQL_PWD environment variable, so that password also never appears on the mysqldump/innobackupex command line.

sql/wsrep_utils.cc

@@ -165,9 +165,10 @@ env::append(const char* val)
             ++len_;
             env_[len_] = NULL;
         }
-        else errno_ = errno;
     }
-    else errno_ = errno;
+
+    /* if either realloc() or strdup() failed, errno had been set */
+    errno_ = errno;
 
     return errno_;
 }