Log Message:
pkgtools/mktool: update to 0.1.20

v0.1.20
 - checksum: Fix paths that don't match distinfo.

v0.1.19
 - fetch: Update to pkgsrc 0.1.29 API.
 - distinfo: Rewrite to use pkgsrc 0.1.29 API.
 - checksum: Rewrite to use pkgsrc 0.1.29 API.
 - Cargo: Bump pkgsrc requirement to 0.1.29.
 - distinfo: Add test for makepatchsum with no patches.
 - checksum: Test specific digest missing message.