Merge recent trunk enhancements, and in particular the improvements to

the b-tree balancing logic, into the sessions branch.

FossilOrigin-Name: 28b044a51215a3f64dafb2cf3b6cb7d2029580ef

src/vdbeblob.c

@@ -155,6 +155,11 @@ int sqlite3_blob_open(
   Parse *pParse = 0;
   Incrblob *pBlob = 0;
 
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) || ppBlob==0 || zTable==0 ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
   flags = !!flags;                /* flags = (flags ? 1 : 0); */
   *ppBlob = 0;