cubicweb #1910869 cubicweb-ctl db-dump --format=portable fails with mssql [validation pending]

the generated file is almost empty.

Caused by cursor.rowcount returning 0 before 1st row has been fetched. See http://code.google.com/p/pyodbc/wiki/Cursor#rowcount

priorityimportant
typebug
done in3.12.10
load0.250
load left0.000
closed by#681ef2a664dd work around cursor.rowcount not returning anything useful before 1st fetch with mssql (closes #1910869)