allow tab in controlCharacterInFilePath

Seems unlikely to have a tab in a path, but it's not a control character
that needs to be prevented either.

Left \n \r \v and \a as other non-threatening control characters
that are still obnoxious to have in a filepath because of how it causes
issues with display and/or with shell scripting.

Annex/UntrustedFilePath.hs

@@ -53,7 +53,12 @@ sanitizeLeadingFilePathCharacter ('/':s) = '_':s
 sanitizeLeadingFilePathCharacter s = s
 
 controlCharacterInFilePath :: FilePath -> Bool
-controlCharacterInFilePath = any isControl
+controlCharacterInFilePath = any (not . safechar)
+  where
+	safechar c
+		| not (isControl c) = True
+		| c == '\t' = True
+		| otherwise = False
 
 {- ../ is a path traversal, no matter where it appears.
  -