D865: obsmarker: fix crash when metadata fields are >255 bytes

[pulkit (Pulkit Goyal)]

pulkit added a comment.


  Also we append the issue number in the commit message at the end like `(issueXXXX)` so that the Bugzilla bot can automatically close that. For reference: https://www.mercurial-scm.org/repo/hg-committed/log?rev=issue&revcount=20

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D865

To: swhitaker, #hg-reviewers, ikostia
Cc: pulkit, ikostia, mercurial-devel