Download from divecomputer: reset progress bar fraction

Otherwise when retrying, the progress bar might already be reset, but
its text might still show 100%.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

desktop-widgets/downloadfromdivecomputer.cpp

@@ -194,6 +194,7 @@ void DownloadFromDCWidget::updateState(states state)
 	else if (state == DOWNLOADING) {
 		timer->start();
 		ui.progressBar->setValue(0);
+		progress_bar_fraction = 0.0;
 		updateProgressBar();
 		ui.progressBar->show();
 		markChildrenAsDisabled();