I just got an issue using subversion 1.7.7 (Tortoise SVN / Windows), I have not found it in the issue database and wanted to submit it to you.
It happened when doing an SVN update on an existing checkout.
In case the image does not come through, the message says the error is in file ‘D:\Development\SVN\Releases\TortoiseSVN-1.7.7\ext\subversion\subversion\libsvn_wc\update_editor.c’ line 2899: assertion failed (status != svn_wc__db_status_normal)
The central repository is managed by USVN and uses SVN 1.6.6. It is access through HTTPS.
Also it may be good for you to know that I had been checking- out the same repository using other credentials (with different access rights) in a separate local folder.
Let me know if you need any more information.