Martin von Zweigbergk <martinvonz@google.com> [Fri, 26 Jan 2018 11:42:47 -0800] rev 35809
unamend: fix command summary line
Before this patch, the docstring started with a newline, which led the
summary line (shown in e.g. `hg help -c`) to be blank.
Differential Revision: https://phab.mercurial-scm.org/D1943