test-fetch: make output stable

tests/test-fetch

@@ -21,5 +21,5 b' hg --cwd b parents -q'
 
 echo c > c/c
 hg --cwd c commit -d '3 0' -Amc
-hg --cwd c fetch ../a
+hg --cwd c fetch -d '4 0' -m 'automated merge' ../a
 ls c

tests/test-fetch.out

@@ -21,7 +21,7 b' adding file changes'
 added 1 changesets with 1 changes to 1 files (+1 heads)
 merging with new head 2:97d72e5f12c7
 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
-new changeset 3:5202af1888fa merges remote changes with local
+new changeset 3:cd3a41621cf0 merges remote changes with local
 a
 b
 c