fix sed in context test

Previous solution included in incorrect 's' in the sed line
intended to remove .repo/repo git from the build context.

Closes-bug: 1893243
Change-Id: I902844f7e3b0f487e4f062d804880e7ad7363b09
Signed-off-by: Scott Little <scott.little@windriver.com>

build-tools/git-utils.sh

@@ -380,7 +380,7 @@ git_test_context () {
     # Limit search to last 500 commits in the interest of speed.
     # I don't expect to be using contexts more than a few weeks old.
     cat "$context" | \
-        sed -e "s/\.repo\/repo/d" \
+        sed -e "/\.repo\/repo/d" \
             -e "s#checkout -f \([a-e0-9]*\)#rev-list --max-count=500 HEAD | \
         grep \1#" > $query