support/download/git: fix formatting of error message

'.' should be at the end of the sentence, not the beginning of a new
line.

Signed-off-by: John Keeping <john@metanate.com>
Cc: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

support/download/git

@@ -130,7 +130,7 @@ fi
 # scratch won't help, so we don't want to trash the repository for a
 # missing commit. We just exit without going through the ERR trap.
 if ! _git rev-parse --quiet --verify "'${cset}^{commit}'" >/dev/null 2>&1; then
-    printf "Commit '%s' does not exist in this repository\n." "${cset}"
+    printf "Commit '%s' does not exist in this repository.\n" "${cset}"
     exit 1
 fi