tests: fix command line overflow on ksh
"<command> `hg manifest`" overflows the puny 1024 byte command line length
limit on AIX default shell ksh. Replace with "hg manifest | xargs <command>".
Mercurial
=========
Mercurial is a fast, easy to use, distributed revision control tool
for software developers.
Basic install:
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
See http://mercurial.selenic.com/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.