[patchbomb] prepend leading zeros in the "[PATCH N of M]" string
Without this patch, if one tries to send a patch bomb with more than 9
patches, the resulting subjects are not easily alphabetically sortable.
For example:
...
[PATCH 9 of 10]
[PATCH 10 of 10]
This patch prepends as many leading zeros as necessary. E.g.,
[PATCH 09 of 10]
or
[PATCH 009 of 100]
35fb62a3a673d5322f6274a44ba6456e5e4b3b37 0 iD8DBQBEYmO2ywK+sNU5EO8RAnaYAKCO7x15xUn5mnhqWNXqk/ehlhRt2QCfRDfY0LrUq2q4oK/KypuJYPHgq1A=
2be3001847cb18a23c403439d9e7d0ace30804e9 0 iD8DBQBExUbjywK+sNU5EO8RAhzxAKCtyHAQUzcTSZTqlfJ0by6vhREwWQCghaQFHfkfN0l9/40EowNhuMOKnJk=