ignore: resolve ignore files relative to repo root (issue4473) (BC)

Previously these would be considered to be relative to the current working
directory. That behavior is both undocumented and doesn't really make sense.
There are two reasonable options for how to resolve relative paths:
- relative to the repo root
- relative to the config file

Resolving these files relative to the repo root matches existing behavior with
hooks. An earlier discussion about this is available at
http://mercurial.markmail.org/thread/tvu7yhzsiywgkjzl.

Thanks to Isaac Jurado <[e-mail]> for the initial patchset that
spurred the discussion.

mercurial/dirstate.py

@@ -130,7 +130,9 b' class dirstate(object):'
         files = [self._join('.hgignore')]
         for name, path in self._ui.configitems("ui"):
             if name == 'ignore' or name.startswith('ignore.'):
-                files.append(util.expandpath(path))
+                # we need to use os.path.join here rather than self._join
+                # because path is arbitrary and user-specified
+                files.append(os.path.join(self._rootdir, util.expandpath(path)))
         return ignore.ignore(self._root, files, self._ui.warn)
 
     @propertycache

mercurial/help/config.txt

@@ -1338,11 +1338,11 b' User interface controls.'
 
 ``ignore``
     A file to read per-user ignore patterns from. This file should be
-    in the same format as a repository-wide .hgignore file. This
-    option supports hook syntax, so if you want to specify multiple
-    ignore files, you can do so by setting something like
-    ``ignore.other = ~/.hgignore2``. For details of the ignore file
-    format, see the ``hgignore(5)`` man page.
+    in the same format as a repository-wide .hgignore file. Filenames
+    are relative to the repository root. This option supports hook syntax,
+    so if you want to specify multiple ignore files, you can do so by
+    setting something like ``ignore.other = ~/.hgignore2``. For details
+    of the ignore file format, see the ``hgignore(5)`` man page.
 
 ``interactive``
     Allow to prompt the user. True or False. Default is True.

tests/test-hgignore.t

@@ -80,13 +80,23 b' Test that patterns from ui.ignore option'
 
 empty out testhgignore
   $ echo > .hg/testhgignore
-  $ echo "glob:*.o" > .hgignore
+
+Test relative ignore path (issue4473):
+
+  $ cat >> $HGRCPATH << EOF
+  > [ui]
+  > ignore.relative = .hg/testhgignorerel
+  > EOF
+  $ echo "glob:*.o" > .hg/testhgignorerel
+  $ cd dir
   $ hg status
   A dir/b.o
   ? .hgignore
   ? a.c
   ? syntax
 
+  $ cd ..
+  $ echo > .hg/testhgignorerel
   $ echo "syntax: glob" > .hgignore
   $ echo "re:.*\.o" >> .hgignore
   $ hg status