Steps to reproduce

1. Add a new SVN property to a file:

   $ svn propset svn:mime-type "application/x-sh" filename
   

2. Commit the changes eg: revision 2

   $ svn diff -r 1:2 filename
   Index: filename
   ===================================================================
   --- filename    (revision 1)
   +++ filename    (revision 2)
   
   Property changes on: filename
   ___________________________________________________________________
   Added: svn:mime-type
   ## -0,0 +1 ##
   +application/x-sh
   \ No newline at end of property
   

3. Change the SVN property value:

   svn propset svn:mime-type "text/x-shellscript" filename
   

4. Commit the changes eg: revision 3

   $ svn diff -r 2:3 filename 
   Index: filename
   ===================================================================
   --- filename    (revision 2)
   +++ filename    (revision 3)
   
   Property changes on: filename
   ___________________________________________________________________
   Modified: svn:mime-type
   ## -1 +1 ##
   -application/x-sh
   +text/x-shellscript
   \ No newline at end of property
   

5. Try to add revision 2 to a review (the checkbox is grey out)
6. Try to add revision 3 to the same review (success)

It seems that the SVN diff for property modification does not show the changes for file content:

$ svn diff -r 2:3 filename 
...
Modified: svn:mime-type
## -1 +1 ##
-application/x-sh
+text/x-shellscript
\ No newline at end of property

FishEye/Crucible think that there is a file content changes from the diff '## -1 +1 ##' and permit the addition of the diff to the review