Add test for unicode branch names.

t/unicode_branch_name.t

@@ -0,0 +1,32 @@
+#!/bin/sh
+
+. $(dirname $0)/test_util.sh
+
+prereq on
+
+# Set up repo foo
+make_repo 'foo'
+foo_commit=$(git -C foo rev-parse HEAD)
+git -C foo branch 💣
+
+# Create new commit such that HEAD isn't the commit we want, since that's
+# necessary for forcing wit into executing git show-ref, which is what triggers
+# the error.
+echo $RANDOM > foo/file
+git -C foo add -A
+git -C foo commit -m "commit2"
+
+# Set locale to ASCII (non-UTF-8) encoding.
+export LANG=C
+export LC_ALL=C
+
+prereq off
+
+wit init myws -a $PWD/foo::💣
+cd myws
+
+foo_ws_commit=$(git -C foo rev-parse HEAD)
+check "foo commit should match the dependency" [ "$foo_ws_commit" = "$foo_commit" ]
+
+report
+finish