Jun Wu <quark@fb.com> [Mon, 28 Aug 2017 16:49:41 -0700] rev 33998
context: make parents and text optional in metadataonlyctx
The metadataonlyctx is to copy an existing context with some minor metadata
changes. If the caller only wants to change "extra", or "user", ideally it
does not have to read and pass "parents" and "text" information.
This patch makes "parents" and "text" optionally to convenient callers.
Differential Revision: https://phab.mercurial-scm.org/D548