convert: correctly convert paths to UTF-8 for Subversion The previous code using encoding.tolocal() only worked by chance in these situations: * The string is ASCII: The fast path was triggered and the string was returned unmodified. * The local encoding is UTF-8: The source and target encoding is the same. * The string is not valid UTF-8 and the native encoding is ISO-8859-1: If the string doesn’t decode using UTF-8, ISO-8859-1 is tried as a fallback. During `hg convert`, the local encoding is always UTF-8. The irony is that in this case, encoding.tolocal() behaves like what someone would expect the reverse function, encoding.fromlocal(), to do. When the locale encoding is ISO-8859-15, trying to convert a SVN repo `/tmp/a€` failed before like this: file:///tmp/a%C2%A4 does not look like a Subversion repository to libsvn version 1.14.0 The correct URL is `file:///tmp/a%E2%82%AC`. Unlike previously (with the ISO-8859-1 fallback), decoding the path using the locale encoding can fail. In this case, we have to bail out, as Subversion won’t be able to do anything useful with the path.

py3: pass URL as str Before the patch, HTTP(S) URLs were never recognized as a Subversion repository on Python 3.

convert: bail out in Subversion source if encountering non-ASCII HTTP(S) URL Before this patch, in the tested case, urllib raised `httplib.InvalidURL: URL can't contain control characters. '/\xff/!svn/ver/0/.svn' (found at least '\xff')`, which resulted in that the URL was never recognized as a Subversion repository. This patch adds a check that bails out if the URL contains non-ASCII characters. The warning is not overly user-friendly, but giving the user something to type into a search engine is definitively better than not explaining why the repository was not recognized. We could support non-ASCII chracters by quoting them before passing them to urllib. However, we would want to be compatible with what the `svn` command does, which converts the URL from the locale encoding to UTF-8, percent-encodes it and sends it to the server. If the locale encoding is not UTF-8, the behavior is IMHO not very intuitive, as the `svn` command may send different (percent-encoded) octets than what was passed on the console. Instead of copying this behavior, we better leave it forbidden.