[PATCH V11] update: fix bare --clean to work on new branch (issue5003) (BC)

[liscju]

# HG changeset patch
# User liscju <piotr.listkiewicz at gmail.com>
# Date 1459834201 -7200
#      Tue Apr 05 07:30:01 2016 +0200
# Node ID 880899828fc8bc6b30876425e87924e4fd8476ee
# Parent  bdba6a2015d0bc57c6e2beab25d138610dcbf360
update: fix bare --clean to work on new branch (issue5003) (BC)

Before this commit bare update --clean on newly created branch
updates to the parent commit, even if there are later commits
on the parent commit's branch. Update to the latest head on the
parent commit's branch instead.

This seems reasonable as clean should discard uncommited changes,
branch is one of them.

diff --git a/mercurial/destutil.py b/mercurial/destutil.py
--- a/mercurial/destutil.py
+++ b/mercurial/destutil.py
@@ -95,9 +95,16 @@ def _destupdatebranch(repo, clean, check
     wc = repo[None]
     movemark = node = None
     currentbranch = wc.branch()
+
+    if clean and wc.p1():
+        currentbranch = repo['.'].branch()
+
     if currentbranch in repo.branchmap():
         heads = repo.branchheads(currentbranch)
         if heads:
+            if clean:
+                repo.ui.warn(_('updating to the head of parent branch %s\n')
+                             % currentbranch)
             node = repo.revs('max(.::(%ln))', heads).first()
         if bookmarks.isactivewdirparent(repo):
             movemark = repo['.'].node()
diff --git a/tests/test-newbranch.t b/tests/test-newbranch.t
--- a/tests/test-newbranch.t
+++ b/tests/test-newbranch.t
@@ -463,3 +463,57 @@ We need special handling for repositorie
   -1 new
 
   $ cd ..
+
+We expect that update --clean discard changes in working directory,
+and updates to the head of parent branch.
+
+  $ hg init updatebareclean
+  $ cd updatebareclean
+  $ hg update --clean
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ touch a
+  $ hg commit -A -m "a"
+  adding a
+  $ touch b
+  $ hg commit -A -m "b"
+  adding b
+  $ touch c
+  $ hg commit -A -m "c"
+  adding c
+  $ hg log
+  changeset:   2:991a3460af53
+  tag:         tip
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     c
+  
+  changeset:   1:0e067c57feba
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     b
+  
+  changeset:   0:3903775176ed
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     a
+  
+  $ hg update -r 1
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg branch new-branch
+  marked working directory as branch new-branch
+  (branches are permanent and global, did you want a bookmark?)
+  $ echo "aa" >> a
+  $ hg update --clean
+  updating to the head of parent branch default
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg status
+  $ hg branch
+  default
+  $ hg parent
+  changeset:   2:991a3460af53
+  tag:         tip
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     c
+  
+