match-trees: factor out fill_tree_desc_strict
match-trees: factor out fill_tree_desc_strict

Deduplicate code by moving tree_desc initialization into a helper
function, fill_tree_desc_strict.  It is like fill_tree_descriptor,
except that it only accepts tree hashes and no tree references (tags,
commits).  No functional change.

Signed-off-by: René Scharfe <5c721353370dda279bee7751cb8d3ff68ef77242@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git