[PATCH 5 of 5] import: introduce --inexact

[timeless]

# HG changeset patch
# User timeless <timeless at mozdev.org>
# Date 1451509906 0
#      Wed Dec 30 21:11:46 2015 +0000
# Node ID 1d608b49e9ec5cec469d24b8d008f5accd806ed3
# Parent  a2350aab89ddc6ddffc556f8ecb0c2398ad348d8
import: introduce --inexact

This allows for a patch where the # Parent node is correct,
but the # Node is incorrect, allowing for memory based
grafting against alternative Nodes merely by doing:
hg export REV | rewrite Parent | hg import --inexact --bypass -

This is a poor man's cross between graft and rebase for
when your working directory is dirty.

diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -888,7 +888,7 @@
 
     rejects = False
     exact = opts.get('exact')
-    usenode = exact
+    usenode = exact or opts.get('inexact')
 
     try:
         cmdline_message = logmessage(ui, opts)
diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -4562,6 +4562,8 @@
      _('commit even if some hunks fail')),
     ('', 'exact', None,
      _('apply patch to the nodes from which it was generated')),
+    ('', 'inexact', None,
+     _('allow the patch to succeed even if the resulting Node differs')),
     ('', 'prefix', '',
      _('apply patch to subdirectory'), _('DIR')),
     ('', 'import-branch', None,
@@ -4604,6 +4606,9 @@
     the patch. This may happen due to character set problems or other
     deficiencies in the text patch format.
 
+    If --inexact is specified, import will set the working directory to
+    the parent of each patch before applying it.
+
     Use --partial to ensure a changeset will be created from the patch
     even if some hunks fail to apply. Hunks that fail to apply will be
     written to a <target-file>.rej file. Conflicts can then be resolved
@@ -4671,6 +4676,7 @@
         opts['date'] = util.parsedate(date)
 
     exact = opts.get('exact')
+    inexact = opts.get('inexact')
     update = not opts.get('bypass')
     if not update and opts.get('no_commit'):
         raise error.Abort(_('cannot use --no-commit with --bypass'))
@@ -4687,6 +4693,11 @@
             raise error.Abort(_('cannot use --exact with --edit'))
         if opts.get('prefix'):
             raise error.Abort(_('cannot use --exact with --prefix'))
+    if inexact:
+        if opts.get('edit'):
+            raise error.Abort(_('cannot use --inexact with --edit'))
+        if opts.get('prefix'):
+            raise error.Abort(_('cannot use --inexact with --prefix'))
 
     base = opts["base"]
     wlock = dsguard = lock = tr = None
diff --git a/tests/test-import-bypass.t b/tests/test-import-bypass.t
--- a/tests/test-import-bypass.t
+++ b/tests/test-import-bypass.t
@@ -22,12 +22,15 @@
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
 
 Test importing an existing revision
-(this also tests that "hg import" disallows combination of '--exact'
-and '--edit')
+(this also tests that "hg import" disallows combination of '--edit'
+and '--exact'/'--inexact')
 
   $ hg import --bypass --exact --edit ../test.diff
   abort: cannot use --exact with --edit
   [255]
+  $ hg import --bypass --inexact --edit ../test.diff
+  abort: cannot use --inexact with --edit
+  [255]
   $ hg import --bypass --exact ../test.diff
   applying ../test.diff
   $ shortlog
@@ -195,6 +198,9 @@
   $ hg import --exact --prefix dir/ ../test.diff
   abort: cannot use --exact with --prefix
   [255]
+  $ hg import --inexact --prefix dir/ ../test.diff
+  abort: cannot use --inexact with --prefix
+  [255]
 
 Test commit editor
 (this also tests that editor is invoked, if the patch doesn't contain
@@ -306,6 +312,42 @@
   |/
   o  0:07f494440405 test 0 0 - default - adda
   
+Test --bypass --inexact
+Without bypass, another object by the same name would
+break imports.
+Exact insists the the Node of the constructed change
+matches that of the patch, but if you are grafting,
+you will not know that node, so you can not use it.
+
+  $ cat ../patch1.diff | \
+  > sed -e 's/07f4944404050f47db2e5c5071e0e84e7a27bba9/d60cb898966615f4364e3e58c880e12d0e651c7d/' \
+  > ../patch1.diff > ../patch1m.diff
+  $ mkdir e
+  $ hg import ../patch1m.diff
+  applying ../patch1m.diff
+  abort: Is a directory: $TESTTMP/repo-multi2/e
+  [255]
+  $ hg import --bypass --exact ../patch1m.diff
+  applying ../patch1m.diff
+  transaction abort!
+  rollback completed
+  abort: patch is damaged or loses information
+  [255]
+  $ hg import --bypass --inexact ../patch1m.diff
+  applying ../patch1m.diff
+  $ shortlog
+  o  4:4e6b5d637a35 test 0 0 - default - adde
+  |
+  o  3:d60cb8989666 test 0 0 - foo - addf
+  |
+  | o  2:16581080145e test 0 0 - default - adde
+  | |
+  @ |  1:4e322f7ce8e3 test 0 0 - foo - changea
+  |/
+  o  0:07f494440405 test 0 0 - default - adda
+  
+  $ hg rollback
+  repository tip rolled back to revision 3 (undo import)
 
   $ cd ..