journal extension uses util.shellquote() to record command line, but
result of it depends on runtime platform: double quotation is used on
Windows and OpenVMS, but single quotation is used otherwise.
test-journal-share.t sometimes specifies commit messages including
white space on command line. It makes journal output depend on runtime
platform, but commit message itself isn't important in this test case.
Rather than put everything into one journal file, split entries up in *shared*
and *local* entries. Working copy changes are local to a specific working copy,
so should remain local only. Other entries are shared with the source if so
configured when the share was created.
When unsharing, any shared journale entries are copied across.
