Fix a problem causing the sessions module to occasionally lose track of rows

with composite primary keys when there are two rows with the same text value
in the leftmost column of the PK.

FossilOrigin-Name: 09aed13678374bf22087cd808808b711dc703b7c18bc8aaf704850611e17f5cd

ext/session/sqlite3session.c

@@ -838,7 +838,6 @@ static int sessionPreupdateEqual(
         }
         if( memcmp(a, z, n) ) return 0;
         a += n;
-        break;
       }
     }
   }