如何防止Visual Studio锁定bin目录中的xml文档文件？

My visual studio solution includes a web application and a unit test application. My web application uses log4net. I want to be able to use msbuild from the command-line to build my solution. However, whenever I build the solution from the command-line, I get build errors because it can't copy log4net.xml to the test project's bin directory. My visual studio solution includes a web applic