Don't close the child item.

A v4l device may become unusable after the first capture (its child source
item may have been faked by libinsane if it had none).

Real scanners sustain both situations so far, i.e., whether the child source
is explicitly closed or not.

Resources/InsaneWidget/InsaneWorker.cpp

@@ -434,7 +434,12 @@ bool InsaneWorker::Scan(const std::string& dir, const std::string& basename,
   if (m_evh)
     m_evh->OnEndScanSession(pageIndex - increment, imageAttributes);
 
-  m_rootSourceItem->close(m_sourceItem); // Child.
+  /*
+   * Don't close the child item.
+   * A v4l device may become unusable after the first capture (its child source
+   * item may have been faked by libinsane if it had none).
+   * Real scanners sustain both situations so far.
+   */
   m_rootSourceItem->close(m_rootSourceItem); // Root.
   return true;
 }