test-convert-hg-source: enforce conversion order with --date

tests/test-convert-hg-source

@@ -11,19 +11,19 b' echo bar > bar'
 hg ci -qAm 'add foo bar' -d '0 0'
 
 echo >> foo
-hg ci -m 'change foo'
+hg ci -m 'change foo' -d '1 0'
 
 hg up -qC 0
 hg copy --after --force foo bar
 hg copy foo baz
-hg ci -m 'make bar and baz copies of foo' -d '1 0'
+hg ci -m 'make bar and baz copies of foo' -d '2 0'
 
 hg merge
-hg ci -m 'merge local copy' -d '2 0'
+hg ci -m 'merge local copy' -d '3 0'
 
 hg up -C 1
 hg merge 2
-hg ci -m 'merge remote copy' -d '3 0'
+hg ci -m 'merge remote copy' -d '4 0'
 
 cd ..
 hg convert --datesort orig new 2>&1 | grep -v 'subversion python bindings could not be loaded'