util: make str(url) return file:/// for abs paths again

util: make str(url) return file:/// for abs paths again

str(url) was recently changed to return only file:/. However, the
canonical way to represent absolute local paths is file:/// [1], which
is also expected by at least hgsubversion.

Relative paths are returned as file:the/relative/path.

[1] http://en.wikipedia.org/wiki/File_URI_scheme

--- a/mercurial/util.py	Thu May 12 18:35:04 2011 -0500
+++ b/mercurial/util.py	Thu May 12 16:41:56 2011 +0200
@@ -1500,6 +1500,8 @@
         'bundle:../foo'
         >>> str(url('path'))
         'path'
+        >>> str(url('file:///tmp/foo/bar'))
+        'file:///tmp/foo/bar'
         >>> print url(r'bundle:foo\bar')
         bundle:foo\bar
         """
@@ -1512,8 +1514,9 @@
             return s
 
         s = self.scheme + ':'
-        if (self.user or self.passwd or self.host or
-            self.scheme and not self.path):
+        if self.user or self.passwd or self.host:
+            s += '//'
+        elif self.scheme and (not self.path or self.path.startswith('/')):
             s += '//'
         if self.user:
             s += urllib.quote(self.user, safe=self._safechars)

--- a/tests/test-url.py	Thu May 12 18:35:04 2011 -0500
+++ b/tests/test-url.py	Thu May 12 16:41:56 2011 +0200
@@ -191,11 +191,23 @@
     >>> str(u)
     'http://foo/bar'
 
+    >>> u = url('file:/foo/bar/baz')
+    >>> u
+    <url scheme: 'file', path: '/foo/bar/baz'>
+    >>> str(u)
+    'file:///foo/bar/baz'
+
     >>> u = url('file:///foo/bar/baz')
     >>> u
     <url scheme: 'file', path: '/foo/bar/baz'>
     >>> str(u)
-    'file:/foo/bar/baz'
+    'file:///foo/bar/baz'
+
+    >>> u = url('file:foo/bar/baz')
+    >>> u
+    <url scheme: 'file', path: 'foo/bar/baz'>
+    >>> str(u)
+    'file:foo/bar/baz'
     """
 
 doctest.testmod(optionflags=doctest.NORMALIZE_WHITESPACE)