webdav: Fix lack of url-escaping of filenames.

inDAVLocation does not url-escape, and so exporting a filename with spaces
to box.com at least resulted in a error 400.

It might also have affected storing keys on a webdav remote, if the key
contained a space or other problem character. Pretty unlikely.

I emailed Clint about the inDAVLocation gotcha, but seems best to fix it
here.

This commit was supported by the NSF-funded DataLad project.

CHANGELOG

@@ -14,6 +14,8 @@ git-annex (6.20170819) UNRELEASED; urgency=medium
     triggered a bug in its webdav support that generates an infinite series
     of redirects. Deal with such problems by assuming such behavior means
     the file is not present.
+  * webdav: Fix lack of url-escaping of filenames. Mostly impacted exports
+    of filenames containing eg spaces.
 
  -- Joey Hess <id@joeyh.name>  Mon, 28 Aug 2017 12:20:59 -0400
 

Remote/WebDAV/DavLocation.hs

@@ -21,14 +21,17 @@ import Utility.Split
 import System.FilePath.Posix -- for manipulating url paths
 import Network.Protocol.HTTP.DAV (inDAVLocation, DAVT)
 import Control.Monad.IO.Class (MonadIO)
+import Network.URI
 import Data.Default
 
 -- Relative to the top of the DAV url.
 type DavLocation = String
 
-{- Runs action in subdirectory, relative to the current location. -}
+{- Runs action with a new location relative to the current location. -}
 inLocation :: (MonadIO m) => DavLocation -> DAVT m a -> DAVT m a
-inLocation d = inDAVLocation (</> d)
+inLocation d = inDAVLocation (</> d')
+  where
+	d' = escapeURIString isUnescapedInURI d
 
 {- The directory where files(s) for a key are stored. -}
 keyDir :: Key -> DavLocation