patchbomb: fix 'echo -en' bashism in test-patchbomb
The echo command doesn't accept options in some shells.
printf is required by the SUSv2 (Single UNIX Specification v2).
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
pulling from ../a
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
(run 'hg update' to get a working copy)
1 files updated, 0 files merged, 1 files removed, 0 files unresolved