remote: write camel-cased *.pushRemote on rename

When a remote is renamed don't change the canonical "*.pushRemote"
form to "*.pushremote". Fixes and tests for a minor bug in
923d4a5ca4 (remote rename/remove: handle branch.<name>.pushRemote
config values, 2020-01-27). See the preceding commit for why this does
& doesn't matter.

While we're at it let's also test that we handle the "*.pushDefault"
key correctly. The code to handle that was added in
b3fd6cbf29 (remote rename/remove: gently handle remote.pushDefault
config, 2020-02-01) and does the right thing, but nothing tested that
we wrote out the canonical camel-cased form.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/remote.c

@@ -746,7 +746,7 @@ static int mv(int argc, const char **argv)
 		}
 		if (info->push_remote_name && !strcmp(info->push_remote_name, rename.old_name)) {
 			strbuf_reset(&buf);
-			strbuf_addf(&buf, "branch.%s.pushremote", item->string);
+			strbuf_addf(&buf, "branch.%s.pushRemote", item->string);
 			git_config_set(buf.buf, rename.new_name);
 		}
 	}

t/t5505-remote.sh

@@ -754,6 +754,7 @@ test_expect_success 'rename a remote' '
 		cd four &&
 		git config branch.main.pushRemote origin &&
 		git remote rename origin upstream &&
+		grep "pushRemote" .git/config &&
 		test -z "$(git for-each-ref refs/remotes/origin)" &&
 		test "$(git symbolic-ref refs/remotes/upstream/HEAD)" = "refs/remotes/upstream/main" &&
 		test "$(git rev-parse upstream/main)" = "$(git rev-parse main)" &&
@@ -770,6 +771,7 @@ test_expect_success 'rename a remote renames repo remote.pushDefault' '
 		cd four.1 &&
 		git config remote.pushDefault origin &&
 		git remote rename origin upstream &&
+		grep pushDefault .git/config &&
 		test "$(git config --local remote.pushDefault)" = "upstream"
 	)
 '