When a 'File Parameter' is given a 'File Location' with forward slashes to use a subdirectory of the workspace (ex: subfolder/input.txt), the file cannot be downloaded from the build's Parameters page. A blank page appears when the links are clicked. If there are no slashes in the 'File Location' the file will download fine.

To Reproduce:
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Create New Build
Check 'This Build is Parameterized'
Add 'File Parameter' with 'file location' = "subfolder/input.txt"
Save
Run Build using a text file named 'testfile.txt' as parameter.
On that Build's info page
Click Parameters
Try and download using the link

Result:
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URL like:
http://JenkinsBox/job/fileParameterBuild/1/parameters/parameter/subdir%2Finput.txt/testfile.txt
Leading to blank white Page

Expected Result:
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Specified File Downloads

Additional Notes:
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The file DOES exist on the server:
C:\BUILD\.jenkins\jobs\fileParameterBuild\builds\2014-01-10_16-52-47\fileParameters\subdir\input.txt