path: add a new argument to control path validation

During pull, unvalidated path might be used, having the option to do so directly will allow use to simplify some code and unlock more `path` usage later in the series.

Differential Revision: https://phab.mercurial-scm.org/D11671

mercurial/utils/urlutil.py

@@ -818,7 +818,14 b' def _chain_path(base_path, ui, paths):'
 class path(object):
     """Represents an individual path and its configuration."""
 
-    def __init__(self, ui=None, name=None, rawloc=None, suboptions=None):
+    def __init__(
+        self,
+        ui=None,
+        name=None,
+        rawloc=None,
+        suboptions=None,
+        validate_path=True,
+    ):
         """Construct a path from its config options.
 
         ``ui`` is the ``ui`` instance the path is coming from.
@@ -856,6 +863,7 b' class path(object):'
         self.rawloc = rawloc
         self.loc = b'%s' % u
 
+        if validate_path:
         self._validate_path()
 
         _path, sub_opts = ui.configsuboptions(b'paths', b'*')