add stacktrace to RetryableException constructor to track down an auth issue

stacks

diff --git a/src/mongo/db/storage/env.cpp b/src/mongo/db/storage/env.cpp
index 3010888..9682308 100644
--- a/src/mongo/db/storage/env.cpp
+++ b/src/mongo/db/storage/env.cpp
@@ -45,6 +45,8 @@ namespace mongo {
 
     namespace storage {
 
+    SimpleMutex RetryableException::_m("RetryableException");
+
         DB_ENV *env;
 
         static int dbt_key_compare(DB *db, const DBT *dbt1, const DBT *dbt2) {
diff --git a/src/mongo/db/storage/exception.h b/src/mongo/db/storage/exception.h
index 6a4ac51..23ca63d 100644
--- a/src/mongo/db/storage/exception.h
+++ b/src/mongo/db/storage/exception.h
@@ -24,6 +24,10 @@
 #include "mongo/util/assert_util.h"
 #include "mongo/util/mongoutils/str.h"
 
+#include "mongo/util/log.h"
+#include "mongo/util/stacktrace.h"
+#include "mongo/util/concurrency/mutex.h"
+
 namespace mongo {
 
     namespace storage {
@@ -85,8 +89,9 @@ namespace mongo {
         };
 
         class RetryableException : public UserException {
+            static SimpleMutex _m;
           public:
-            RetryableException(int code, const std::string &msg) : UserException(code, msg) {}
+            RetryableException(int code, const std::string &msg) : UserException(code, msg) { SimpleMutex::scoped_lock lk(_m); LOG(0) << "throwing retryable exception" << endl; printStackTrace(); }
             virtual ~RetryableException() throw() {}
 
             class MvccDictionaryTooNew;