port mirror does not indicate failure when checksum verification fails

[ryandesign (Ryan Carsten Schmidt)]

port mirror correctly returns an error code if fetch fails. For example if I modify the zlib port to fetch a nonexistent version:

$ sudo /opt/local/bin/port mirror zlib; echo $?
--->  Fetching distfiles for zlib
--->  Attempting to fetch zlib-1.2.1111.tar.xz from https://distfiles.macports.org/zlib
--->  Attempting to fetch zlib-1.2.1111.tar.xz from http://www.zlib.net/
Error: Failed to mirror zlib: The requested URL returned error: 404 Not Found
Error: See /opt/local/var/macports/logs/_Users_rschmidt_macports_macports-ports-svn-trunk_archivers_zlib/zlib/main.log for details.
Error: Follow https://guide.macports.org/#project.tickets to report a bug.
Error: Processing of port zlib failed
1

But if fetch succeeds but checksum verification fails, it does not indicate this. For example if I deliberately make the checksum of the zlib port incorrect:

$ sudo /opt/local/bin/port mirror zlib; echo $?
--->  Fetching distfiles for zlib
--->  Attempting to fetch zlib-1.2.11.tar.xz from https://distfiles.macports.org/zlib
Error: Checksum (rmd160) mismatch for zlib-1.2.11.tar.xz                             
0

We already tell people to run port -p mirror if they want to mirror all files and proceed past errors, so fixing it to correctly indicate its error status seems like the right thing to do.

[jmroot (Joshua Root)]

In 7ada403f32369d9fcf15394be76d8adb8487a410/macports-base (master):

portmirror: indicate error when checksum fails

Closes: #56008