Windows: Support urls like "file:///c:/path"

That is a legal url, but parseUrl parses it to "/c:/path"
which is not a valid path on Windows. So as a workaround, use
parseURIPortable everywhere, which removes the leading slash when
run on windows.

Note that if an url is parsed like this and then serialized back
to a string, it will be different from the input. Which could
potentially be a problem, but is probably not in practice.

An alternative way to do it would be to have an uriPathPortable
that fixes up the path after parsing. But it would be harder to
make sure that is used everywhere, since uriPath is also used
when constructing an URI.

It's also worth noting that System.FilePath.normalize "/c:/path"
yields "c:/path". The reason I didn't use it is that it also
may change "/" to "\" in the path and I wanted to keep the url
changes minimal. Also noticed that convertToWindowsNativeNamespace
handles "/c:/path" the same as "c:/path".

Sponsored-By: the NIH-funded NICEMAN (ReproNim TR&D3) project

Command/AddUrl.hs

@@ -31,6 +31,7 @@ import Logs.Location
 import Utility.Metered
 import Utility.HtmlDetect
 import Utility.Path.Max
+import Utility.Url (parseURIPortable)
 import qualified Utility.RawFilePath as R
 import qualified Annex.Transfer as Transfer
 
@@ -220,7 +221,7 @@ downloadRemoteFile addunlockedmatcher r o uri file sz = checkCanAdd o file $ \ca
 	af = AssociatedFile (Just file)
 
 startWeb :: AddUnlockedMatcher -> AddUrlOptions -> SeekInput -> URLString -> CommandStart
-startWeb addunlockedmatcher o si urlstring = go $ fromMaybe bad $ parseURI urlstring
+startWeb addunlockedmatcher o si urlstring = go $ fromMaybe bad $ parseURIPortable urlstring
   where
 	bad = fromMaybe (giveup $ "bad url " ++ urlstring) $
 		Url.parseURIRelaxed $ urlstring

Command/FromKey.hs

@@ -18,6 +18,7 @@ import Annex.Link
 import Annex.FileMatcher
 import Annex.Ingest
 import Git.FilePath
+import Utility.Url
 
 import Network.URI
 
@@ -89,7 +90,7 @@ keyOpt :: String -> Key
 keyOpt = either giveup id . keyOpt'
 
 keyOpt' :: String -> Either String Key
-keyOpt' s = case parseURI s of
+keyOpt' s = case parseURIPortable s of
 	Just u | not (isKeyPrefix (uriScheme u)) ->
 		Right $ Backend.URL.fromUrl s Nothing
 	_ -> case deserializeKey s of