tests: de-flake test-narrow-share.t by making dirstate predictable

test-narrow-share.t was sometimes (~0.5% on my machine) failing like this:

  @@ -61,7 +61,7 @@
     A d3/g
     $ hg -R main debugdirstate --no-dates
     n 644          2 set                 d1/f
  -  n 644          2 unset               d3/f
  +  n 644          2 set                 d3/f
     a   0         -1 unset               d3/g
     n 644          2 set                 d5/f
     n 644          2 set                 d7/f

The timestamp for d3/f would get set if it was determined at some
point that it was clean. That check is usually done when the user runs
`hg st`. We don't do that before the failure in the test case, but it
happens at the end of the `hg clone` call. So if the file system's
time happens to roll over after the clone's working copy has been
written, but before its (final) dirstate has been written, we can end
up with a set timestamp there.

This patch makes it consistent by sleeping for 2 seconds so the
timestamp gets reliably set.

Differential Revision: https://phab.mercurial-scm.org/D5568

tests/test-narrow-share.t

@@ -44,6 +44,14 b''
 
 Narrow the share and check that the main repo's working copy gets updated
 
+# Make sure the files that are supposed to be known-clean get their timestamps set in the dirstate
+  $ sleep 2
+  $ hg -R main st
+  $ hg -R main debugdirstate --no-dates
+  n 644          2 set                 d1/f
+  n 644          2 set                 d3/f
+  n 644          2 set                 d5/f
+  n 644          2 set                 d7/f
 # Make d3/f dirty
   $ echo x >> main/d3/f
   $ echo y >> main/d3/g
@@ -58,7 +66,7 b' Narrow the share and check that the main'
   A d3/g
   $ hg -R main debugdirstate --no-dates
   n 644          2 set                 d1/f
-  n 644          2 unset               d3/f
+  n 644          2 set                 d3/f
   a   0         -1 unset               d3/g
   n 644          2 set                 d5/f
   n 644          2 set                 d7/f