scmutil: add function to help handling workingctx in arithmetic operation
It's unfortunate that workingctx revision is None, which doesn't work well in
arithmetic operation or comparison. This function is trivial but will be used
in several places.
#require unix-permissions no-root
$ hg init t
$ cd t
$ echo foo > a
$ hg add a
$ hg commit -m "1"
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
$ chmod -r .hg/store/data/a.i
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
abort: Permission denied: $TESTTMP/t/.hg/store/data/a.i
[255]
$ chmod +r .hg/store/data/a.i
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
$ chmod -w .hg/store/data/a.i
$ echo barber > a
$ hg commit -m "2"
trouble committing a!
abort: Permission denied: $TESTTMP/t/.hg/store/data/a.i
[255]
$ chmod -w .
$ hg diff --nodates
diff -r 2a18120dc1c9 a
--- a/a
+++ b/a
@@ -1,1 +1,1 @@
-foo
+barber
$ chmod +w .
$ chmod +w .hg/store/data/a.i
$ mkdir dir
$ touch dir/a
$ hg status
M a
? dir/a
$ chmod -rx dir
$ hg status
dir: Permission denied
M a
Reenable perm to allow deletion:
$ chmod +rx dir
$ cd ..