patch._applydiff: resolve prefix with respect to the cwd

This has several advantages compared to resolving it relative to the root:

- '--prefix .' works as expected.
- consistent with upcoming 'hg diff' option to produce relative patches

(I made sure to put in the (glob) annotations this time!)

mercurial/commands.py

@@ -4066,7 +4066,7 b' def identify(ui, repo, source=None, rev='
     ('', 'exact', None,
      _('apply patch to the nodes from which it was generated')),
     ('', 'prefix', '',
-     _('apply patch to directory relative to the root'), _('DIR')),
+     _('apply patch to subdirectory'), _('DIR')),
     ('', 'import-branch', None,
      _('use any branch information in patch (implied by --exact)'))] +
     commitopts + commitopts2 + similarityopts,

mercurial/patch.py

@@ -17,6 +17,7 b' from i18n import _'
 from node import hex, short
 import cStringIO
 import base85, mdiff, scmutil, util, diffhelpers, copies, encoding, error
+import pathutil
 
 gitre = re.compile('diff --git a/(.*) b/(.*)')
 tabsplitter = re.compile(r'(\t+|[^\t]+)')
@@ -1795,8 +1796,10 b' def _applydiff(ui, fp, patcher, backend,'
                eolmode='strict'):
 
     if prefix:
-        # clean up double slashes, lack of trailing slashes, etc
-        prefix = util.normpath(prefix) + '/'
+        prefix = pathutil.canonpath(backend.repo.root, backend.repo.getcwd(),
+                                    prefix)
+        if prefix != '':
+            prefix += '/'
     def pstrip(p):
         return pathtransform(p, strip - 1, prefix)[1]
 

tests/test-import-git.t

@@ -626,6 +626,33 b' Prefix with strip, renames, creates etc'
   adding dir/d
   adding dir/dir2/b
   adding dir/dir2/c
+
+prefix '.' is the same as no prefix
+  $ hg import --no-commit --prefix . - <<EOF
+  > diff --git a/dir/a b/dir/a
+  > --- /dev/null
+  > +++ b/dir/a
+  > @@ -0,0 +1 @@
+  > +aaaa
+  > diff --git a/dir/d b/dir/d
+  > --- a/dir/d
+  > +++ b/dir/d
+  > @@ -1,1 +1,2 @@
+  >  d
+  > +dddd
+  > EOF
+  applying patch from stdin
+  $ cat dir/a
+  aaaa
+  $ cat dir/d
+  d
+  dddd
+  $ hg revert -aC
+  forgetting dir/a (glob)
+  reverting dir/d (glob)
+  $ rm dir/a
+
+prefix with default strip
   $ hg import --no-commit --prefix dir/ - <<EOF
   > diff --git a/a b/a
   > --- /dev/null
@@ -649,10 +676,10 b' Prefix with strip, renames, creates etc'
   forgetting dir/a (glob)
   reverting dir/d (glob)
   $ rm dir/a
-(test that prefixes are relative to the root)
+(test that prefixes are relative to the cwd)
   $ mkdir tmpdir
   $ cd tmpdir
-  $ hg import --no-commit -p2 --prefix dir/ - <<EOF
+  $ hg import --no-commit -p2 --prefix ../dir/ - <<EOF
   > diff --git a/foo/a b/foo/a
   > new file mode 100644
   > --- /dev/null