This commit fixes

  - errno handling in wsp::env::append() method, where error could be returned by mistake
  - return code of sst_prepare_other() when pthread_create() fails - it was returning positive error code which by convention is treated as success.

sql/wsrep_utils.cc

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