Why does 'hg verify' lock?

[Jens.Wulf at sew-eurodrive.de]

Hi,

to the .hg/hgrc of a central repo on a network share I added
  [hooks]
  changegroup = hg verify
in order to get a verify everytime someone pushes to it. The hook is executed, however, it does not work because the push seems to lock the repo and hg verify seems to refuse using a locked repo:

pushing to ..\ibntest\
searching for changes
common changesets up to af2ac2fa13dd
2 changesets found
List of changesets:
26eebcb66b5033e5140401a32375620a77e15650
1a7c9bfa64b25388a0315f30ea131591602b1018
adding changesets
add changeset 26eebcb66b50
add changeset 1a7c9bfa64b2
adding manifests
adding file changes
adding .hgignore revisions
adding zutaten/lsm_ibn.mon revisions
added 2 changesets with 2 changes to 2 files
updating the branch cache
running hook changegroup: hg verify
waiting for lock on repository C:\vss\eetrv6\Pro1734_5401\ibntest held by 'ws2kbru1634:1340'

Best regards,
Jens