title: "#" sign cannot be in csproj/sln pathname when debugging Razor class library in VS2017
body: <p>During learning the Razor class libraries (RCL) features I have found very strange error, which took me hours to determine. I cannot have <code>#</code> sign in the pathname, when trying to debug the project.</p>
  
  <p>Steps to reproduce:</p>
  
  <ol>
  <li>Clone repository <a href="https://github.com/zoka-cz/CSharpDirNameProblem" rel="nofollow noreferrer">git@github.com:zoka-cz/CSharpDirNameProblem.git</a> into any directory you want (iteration 1 - ensure <code>#</code> is not anywhere in the pathname like <code>c:\tmp\CSharpDirNameProblem\</code> | iteration 2 - ensure the <code>#</code> is in the directory name e.g. <code>c:\tmp\C#\CSharpDirNameProblem\</code>)</li>
  <li>Open solution <code>src\CSharpDirNameProblem.sln</code> (I have VS2017, not sure about other versions)</li>
  <li>Set <code>WebApplication1</code> as startup project and run.</li>
  <li>In browser opened click <code>About</code> page and observe different results.</li>
  <li>Go to second iteration from 1st point, otherwise finished.</li>
  </ol>
  
  <p>The mentioned repository is minimal setup to reproduce the issue. Firstly it was created RCL project with few razor views. Then the <code>WebApplication</code> (MVC web application) project was created, the RCL added as reference, the <code>About</code> page was changed to test RCL project views. Very simple.
  But, when there is <code>#</code> sign in the path of my project, then it fails to find the views from RCL. The webapplication works, but it does not find the RCL views. You may imagine the hours I have spent finding the problem. Now I know that I cannot have <code>#</code> in the name, but I would like to know why, and if it is possible to work around this problem (lot of my project resides in my <code>...Projects\C#</code> directory). </p>
  
  <p>Has anyone the idea what causes the issue? Is it IIS Express? Is it Visual studio? Is it problem of the AspNetCore? Can I fix it alone somehow? May I find the source of problem by myself? Or maybe report it somewhere?</p>