go-1.13:error:patch Failed to patch go

[iefdev (Eric F)]

Upgrading go failed:

:notice:patch --->  Applying patches to go
:info:patch --->  Applying dist-support-BOOT_GO_LDFLAGS.patch
:debug:patch Environment: 
:debug:patch CC_PRINT_OPTIONS='YES'
:debug:patch CC_PRINT_OPTIONS_FILE='/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_go/go/work/.CC_PRINT_OPTIONS'
:debug:patch CPATH='/opt/local/include'
:debug:patch LIBRARY_PATH='/opt/local/lib'
:debug:patch MACOSX_DEPLOYMENT_TARGET='10.7'
:info:patch Executing:  cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_go/go/work/go" && /usr/bin/patch -p0 < '/opt/local/var/macports/sources/rsync.macports.org/macports/release/tarballs/ports/lang/go/files/dist-support-BOOT_GO_LDFLAGS.patch'
:debug:patch system:  cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_go/go/work/go" && /usr/bin/patch -p0 < '/opt/local/var/macports/sources/rsync.macports.org/macports/release/tarballs/ports/lang/go/files/dist-support-BOOT_GO_LDFLAGS.patch'
:info:patch patching file src/cmd/dist/build.go
:info:patch Reversed (or previously applied) patch detected!  Assume -R? [n] 
:info:patch Apply anyway? [n] 
:info:patch Skipping patch.
:info:patch 3 out of 3 hunks ignored -- saving rejects to file src/cmd/dist/build.go.rej
:info:patch Command failed:  cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_go/go/work/go" && /usr/bin/patch -p0 < '/opt/local/var/macports/sources/rsync.macports.org/macports/release/tarballs/ports/lang/go/files/dist-support-BOOT_GO_LDFLAGS.patch'
:info:patch Exit code: 1
:error:patch Failed to patch go: command execution failed
:debug:patch Error code: CHILDSTATUS 4508 1
:debug:patch Backtrace: command execution failed
:debug:patch     while executing
:debug:patch "system {*}$notty {*}$nice $fullcmdstring"
:debug:patch     invoked from within
:debug:patch "command_exec patch "" "< '$patch'""
:debug:patch     (procedure "portpatch::patch_main" line 41)
:debug:patch     invoked from within
:debug:patch "$procedure $targetname"
:error:patch See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_go/go/main.log for details.

Uninstalled, and cleaned out go completely - still the same thing.

Reinstalling 1.12.9 worked fine (same patches).