Bug in the SQLGetDiagRec function of psqlodbc

There seems to be a bug in the SQLGetDiagRec function - it always returns
the oldest error message. For example, after I run two invalid queries,
calling SQLGetDiagRec gives me the error message for the first query
instead of the second one. However, according to the specs
<https://msdn.microsoft.com/en-us/library/ms716256(v=vs.85).aspx>,

*SQLGetDiagRec* retrieves only the diagnostic information most recently
> associated with the handle specified in the *Handle* argument. If the
> application calls another ODBC function, except *SQLGetDiagRec*,
> *SQLGetDiagField*, or *SQLError*, any diagnostic information from the
> previous calls on the same handle is lost.

My psqlodbcw.so file was built from the HEAD of
http://git.postgresql.org/git/psqlodbc.git using Homebrew
<https://github.com/Homebrew/homebrew/blob/master/Library/Formula/psqlodbc.rb#L17>
on
Mac OS X. Here is the code for demonstrating this issue:

#include <stdio.h>
#include <sql.h>
#include <sqlext.h>

void printError(SQLHANDLE handle) {
char message[256];
SQLSMALLINT i = 0;
while (SQLGetDiagRec(SQL_HANDLE_DBC, handle, ++i, NULL, NULL,
(SQLCHAR*)message, sizeof(message), NULL) != SQL_NO_DATA) {
printf("%s\n", message);
}
}

BOOL runQuery(SQLHSTMT stmt, char* query) {
SQLRETURN ret = SQLExecDirect(stmt, (SQLCHAR*)query, SQL_NTS);
printf("Query: %s\n", query);
return SQL_SUCCEEDED(ret);
}

int main(int argc, const char * argv[]) {
SQLHENV env;
SQLHDBC dbc;
SQLHSTMT stmt;

SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &env);
SQLSetEnvAttr(env, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, 0);
SQLAllocHandle(SQL_HANDLE_DBC, env, &dbc);

char* connStr =
"Driver=/usr/local/Cellar/psqlodbc/HEAD/lib/psqlodbcw.so;Server=localhost;Database=postgres";
if (SQLDriverConnect(dbc, NULL, (SQLCHAR*)connStr, SQL_NTS, NULL, 0,
NULL, SQL_DRIVER_NOPROMPT) != SQL_SUCCESS) {
printf("Unable to connect to database\n");
return 1;
}

SQLAllocHandle(SQL_HANDLE_STMT, dbc, &stmt);
for (int i = 0; i < 3; ++i) {
char query[50];
sprintf(query, "SELECT * FROM t%d", i);
if (!runQuery(stmt, query)) {
printError(dbc); // this always prints 'ERROR: relation "t0" does not
exist' - that's wrong!
}
}

SQLDisconnect(dbc);
SQLFreeHandle(SQL_HANDLE_STMT, stmt);
SQLFreeHandle(SQL_HANDLE_DBC, dbc);
SQLFreeHandle(SQL_HANDLE_ENV, env);
return 0;
}