Prevent deadlock of database mutex

src/crypto.c

@@ -365,7 +365,11 @@ int sqlite3CodecAttach(sqlite3* db, int nDb, const void *zKey, int nKey) {
     /* point the internal codec argument against the contet to be prepared */
     rc = sqlcipher_codec_ctx_init(&ctx, pDb, pDb->pBt->pBt->pPager, fd, zKey, nKey); 
 
-    if(rc != SQLITE_OK) return rc; /* initialization failed, do not attach potentially corrupted context */
+    if(rc != SQLITE_OK) {
+      /* initialization failed, do not attach potentially corrupted context */
+      sqlite3_mutex_leave(db->mutex);
+      return rc;
+    }
 
     sqlite3pager_sqlite3PagerSetCodec(sqlite3BtreePager(pDb->pBt), sqlite3Codec, NULL, sqlite3FreeCodecArg, (void *) ctx);