i18n: submodule: escape shell variables inside eval_gettext

According to the gettext manual [1], references to shell variables inside
eval_gettext call must be escaped so that eval_gettext receives the
translatable string before the variable values are substituted into it.

[1] http://www.gnu.org/software/gettext/manual/html_node/Preparing-Shell-Scripts.htmlSigned-off-by: NVasco Almeida <vascomalmeida@sapo.pt>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

git-submodule.sh

@@ -647,7 +647,7 @@ cmd_update()
 			remote_name=$(sanitize_submodule_env; cd "$sm_path" && get_default_remote)
 			sha1=$(sanitize_submodule_env; cd "$sm_path" &&
 				git rev-parse --verify "${remote_name}/${branch}") ||
-			die "$(eval_gettext "Unable to find current ${remote_name}/${branch} revision in submodule path '\$sm_path'")"
+			die "$(eval_gettext "Unable to find current \${remote_name}/\${branch} revision in submodule path '\$sm_path'")"
 		fi
 
 		if test "$subsha1" != "$sha1" || test -n "$force"
@@ -671,7 +671,7 @@ cmd_update()
 				# not be reachable from any of the refs
 				is_tip_reachable "$sm_path" "$sha1" ||
 				fetch_in_submodule "$sm_path" "$sha1" ||
-				die "$(eval_gettext "Fetched in submodule path '\$displaypath', but it did not contain $sha1. Direct fetching of that commit failed.")"
+				die "$(eval_gettext "Fetched in submodule path '\$displaypath', but it did not contain \$sha1. Direct fetching of that commit failed.")"
 			fi
 
 			must_die_on_failure=