getpatch: Use a single method to retrieve patch names and URLs.

[rakuco]

Summary

Instead of retrieving patch URLs and names separately, do so in a single shot and store the information in a single data structure. Not only does this simplify the code a little, but it also allows for better error messages in case something goes wrong and a certain patch needs to be skipped.

[sbz]

Committed in r362667 . Thanks rakuco, great stuff!