[PATCH V2] update: warn if cwd was deleted

[Stanislau Hlebik]

# HG changeset patch
# User Stanislau Hlebik <stash at fb.com>
# Date 1472848944 25200
#      Fri Sep 02 13:42:24 2016 -0700
# Node ID 374caff3f6ba064070d01329eec1bd33a6a45370
# Parent  318e2b600b80e4ed3c6f37df46ec7544f60d4c0b
update: warn if cwd was deleted

During update directories are deleted as soon as they have no entries.
But if current working directory is deleted then it cause problems
in complex commands like 'hg split'. This commit adds a warning
that will help users figure the problem faster.

diff --git a/mercurial/merge.py b/mercurial/merge.py
--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -1043,7 +1043,19 @@
             repo.ui.note(_("removing %s\n") % f)
         audit(f)
         try:
-            unlink(wjoin(f), ignoremissing=True)
+            try:
+                cwd = os.getcwd()
+            except OSError:
+                cwd = None
+            path = wjoin(f)
+            unlink(path, ignoremissing=True)
+            try:
+                os.getcwd()
+            except OSError:
+                # Print a warning if cwd was deleted
+                if cwd and path.startswith(cwd):
+                    repo.ui.warn(_("cwd was deleted - consider "
+                                   "changing cwd to repo root\n"))
         except OSError as inst:
             repo.ui.warn(_("update failed to remove %s: %s!\n") %
                          (f, inst.strerror))
diff --git a/tests/test-rebase-scenario-global.t b/tests/test-rebase-scenario-global.t
--- a/tests/test-rebase-scenario-global.t
+++ b/tests/test-rebase-scenario-global.t
@@ -758,6 +758,7 @@
   $ hg commit -m 'second source with subdir'
   $ hg rebase -b . -d 1 --traceback
   rebasing 2:779a07b1b7a0 "first source commit"
+  cwd was deleted - consider changing cwd to repo root
   rebasing 3:a7d6f3a00bf3 "second source with subdir" (tip)
   saved backup bundle to $TESTTMP/cwd-vanish/.hg/strip-backup/779a07b1b7a0-853e0073-backup.hg (glob)
 
diff --git a/tests/test-update-names.t b/tests/test-update-names.t
--- a/tests/test-update-names.t
+++ b/tests/test-update-names.t
@@ -72,3 +72,14 @@
   $ cd ..
 
 #endif
+
+Test that warning is printed if cwd is deleted during update
+  $ hg init r4 && cd r4
+  $ mkdir dir
+  $ cd dir
+  $ echo a > a
+  $ echo b > b
+  $ hg add a b
+  $ hg ci -m "file and dir"
+  $ hg up -q null
+  cwd was deleted - consider changing cwd to repo root