tdb2: don't be fascist when TDB_VERSION1 is specified.

We currently insist that a tdb file be a version1 file if tdb_open() is
passed the TDB_VERSION1 flag; we fail if it's actually a tdb2.

But that makes generic wrappers harder, and is unlikely to be what the
user wants: if they do, they can check tdb_get_flags() & TDB_VERSION1
after opening.

ccan/tdb2/open.c

@@ -647,12 +647,9 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
 		goto fail;
 	}
 
+	/* This is a version2 tdb. */
 	if (tdb->flags & TDB_VERSION1) {
-		ecode = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
-				   "tdb_open:"
-				   " %s does not need TDB_VERSION1",
-				   name);
-		goto fail;
+		tdb->flags &= ~TDB_VERSION1;
 	}
 
 	tdb2_context_init(tdb);

ccan/tdb2/test/api-tdb1-flag-removal.c

@@ -0,0 +1,38 @@
+#include <ccan/tdb2/tdb2.h>
+#include <ccan/tap/tap.h>
+#include <ccan/hash/hash.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "logging.h"
+
+int main(int argc, char *argv[])
+{
+	unsigned int i;
+	struct tdb_context *tdb;
+	int flags[] = { TDB_DEFAULT, TDB_NOMMAP,
+			TDB_CONVERT, TDB_NOMMAP|TDB_CONVERT };
+
+	plan_tests(sizeof(flags) / sizeof(flags[0]) * 3 + 1);
+	for (i = 0; i < sizeof(flags) / sizeof(flags[0]); i++) {
+		tdb = tdb_open("run-12-store.tdb", flags[i],
+			       O_RDWR|O_CREAT|O_TRUNC, 0600, &tap_log_attr);
+		if (!ok1(tdb))
+			continue;
+
+		tdb_close(tdb);
+
+		tdb = tdb_open("run-12-store.tdb", flags[i] | TDB_VERSION1,
+			       O_RDWR, 0600, &tap_log_attr);
+		if (!ok1(tdb))
+			continue;
+		/* It's not a version1 */
+		ok1(!(tdb_get_flags(tdb) & TDB_VERSION1));
+
+		tdb_close(tdb);
+	}
+
+	ok1(tap_log_messages == 0);
+	return exit_status();
+}