I faced this issue while updating the my svn repository. The error was :
Unable to create pristine install stream
The first solution is running an svn cleanup command or do cleanup using any svn client like the tortoise.
#2. Deletion of tmp
The second solution is the deletion of tmp folder which is available in the .svn folder. After deletion creates again tmp folder in it
#3 Creation of tmp folder
This issue also due to the unavailable tmp folder in .svn folder. So create tmp folder in the .svn folder.
In windows machine by default all folders started with a dot (.) are hidden. So make it visible first.