remotefilelog: avoid accessing repo instance after dispatch Upstream commit c5e6c1ba1c79 (hg: don't reuse repo instance after unshare(), 2018-09-12) poisoned the repo instance after unshare(). That made `hg unshare` fail with remotefilelog because we tried to close the fileserverclient after dispatch by accessing it via the repo. This patch fixes that by storing the reference to the fileserverclient at the beginning of dispatch. An analogous patch was sent for remotefilelog version in FB's hg-experimental as D5246. Differential Revision: https://phab.mercurial-scm.org/D5253