$ 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

  checking changesets

  checking manifests

  crosschecking files in changesets and manifests

  checking files

  abort: Permission denied: .*

  $ chmod +r .hg/store/data/a.i

  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

  trouble committing a!

  abort: Permission denied: .*

  $ 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