First, I really don't believe this is a bug but I don't see another area that would be fitting for this issue.
My Joomla! installation is reporting an update for SecurityCheck Pro to 3.2.1 but all I get is this when updating:
Copy failed: /var/www/joomla/tmp/install_5f5a03e0002f9/com_securitycheckpro/frontend/index.html to /var/www/joomla/components/com_securitycheckpro/index.html
JInstaller: :Install: Failed to copy file /var/www/joomla/tmp/install_5f5a03e0002f9/com_securitycheckpro/frontend/index.html to /var/www/joomla/components/com_securitycheckpro/index.html
Component Update: Failed to copy site files.
Before updating ensure that the update is compatible with your Joomla! installation.
You are strongly advised to make a backup of your installation before you start updating.
I suspect this is an issue folder permissions within my site as I have another component that's showing an update available but generates the same error when updating.
Apache logs aren't showing any errors so I'm sort of lost as to where to look at this point.
OK, I'm putting on "The Cone of Shame" now. Sure enough there were several sub-folders owned by user and group "root" that should not have been there. A quick chown -R to www-date:www-data and *poof* ... problem solved.