Every time before sending a PR I like to run ./scripts/build-test-lint.sh to make sure the CI won't complain about anything.

The problem is that this script attempts to install golangci-lint, which causes modifications to go.mod/go.sum. This PR backs up and restores those files before and after linting.

Ideally instead of this hacky backing up/restoring we'd use go gets -mod=readonly option, but that still modifies go.sum. This will be fixed in go 1.13 apparently. golang/go#30667

Fixes projectcontour#1377

BREAKING CHANGE

We build with -mod=readonly so that the build will fail if anything is
out of date in our go.mod file. golang/go#30667 changed the behaviour of
the go tool to require that go.mod AND go.sum be up to date so this
means I cannot use my hack of .gitignoring the go.sum file.

This means when you pull this commit you will probably have to delete
your local go.sum working copy. If we're lucky then you shouldn't need
to change it after that. If we're not lucky, the bloody thing will
always be dirty and we'll waste a lot of time telling people to revert
their changes to this file. C'est la vie.

Signed-off-by: Dave Cheney <dave@cheney.net>

Fixes projectcontour#1377

BREAKING CHANGE

We build with -mod=readonly so that the build will fail if anything is
out of date in our go.mod file. golang/go#30667 changed the behaviour of
the go tool to require that go.mod AND go.sum be up to date so this
means I cannot use my hack of .gitignoring the go.sum file.

This means when you pull this commit you will probably have to delete
your local go.sum working copy. If we're lucky then you shouldn't need
to change it after that. If we're not lucky, the bloody thing will
always be dirty and we'll waste a lot of time telling people to revert
their changes to this file. C'est la vie.

Signed-off-by: Dave Cheney <dave@cheney.net>

Fixes #1377

BREAKING CHANGE

We build with -mod=readonly so that the build will fail if anything is
out of date in our go.mod file. golang/go#30667 changed the behaviour of
the go tool to require that go.mod AND go.sum be up to date so this
means I cannot use my hack of .gitignoring the go.sum file.

This means when you pull this commit you will probably have to delete
your local go.sum working copy. If we're lucky then you shouldn't need
to change it after that. If we're not lucky, the bloody thing will
always be dirty and we'll waste a lot of time telling people to revert
their changes to this file. C'est la vie.

Signed-off-by: Dave Cheney <dave@cheney.net>

Fixes projectcontour#1377

BREAKING CHANGE

We build with -mod=readonly so that the build will fail if anything is
out of date in our go.mod file. golang/go#30667 changed the behaviour of
the go tool to require that go.mod AND go.sum be up to date so this
means I cannot use my hack of .gitignoring the go.sum file.

This means when you pull this commit you will probably have to delete
your local go.sum working copy. If we're lucky then you shouldn't need
to change it after that. If we're not lucky, the bloody thing will
always be dirty and we'll waste a lot of time telling people to revert
their changes to this file. C'est la vie.

Signed-off-by: Dave Cheney <dave@cheney.net>

Fixes projectcontour#1377

BREAKING CHANGE

We build with -mod=readonly so that the build will fail if anything is
out of date in our go.mod file. golang/go#30667 changed the behaviour of
the go tool to require that go.mod AND go.sum be up to date so this
means I cannot use my hack of .gitignoring the go.sum file.

This means when you pull this commit you will probably have to delete
your local go.sum working copy. If we're lucky then you shouldn't need
to change it after that. If we're not lucky, the bloody thing will
always be dirty and we'll waste a lot of time telling people to revert
their changes to this file. C'est la vie.

Signed-off-by: Dave Cheney <dave@cheney.net>

Fixes projectcontour#1377

BREAKING CHANGE

We build with -mod=readonly so that the build will fail if anything is
out of date in our go.mod file. golang/go#30667 changed the behaviour of
the go tool to require that go.mod AND go.sum be up to date so this
means I cannot use my hack of .gitignoring the go.sum file.

This means when you pull this commit you will probably have to delete
your local go.sum working copy. If we're lucky then you shouldn't need
to change it after that. If we're not lucky, the bloody thing will
always be dirty and we'll waste a lot of time telling people to revert
their changes to this file. C'est la vie.

Signed-off-by: Dave Cheney <dave@cheney.net>

Fixes projectcontour#1377

BREAKING CHANGE

We build with -mod=readonly so that the build will fail if anything is
out of date in our go.mod file. golang/go#30667 changed the behaviour of
the go tool to require that go.mod AND go.sum be up to date so this
means I cannot use my hack of .gitignoring the go.sum file.

This means when you pull this commit you will probably have to delete
your local go.sum working copy. If we're lucky then you shouldn't need
to change it after that. If we're not lucky, the bloody thing will
always be dirty and we'll waste a lot of time telling people to revert
their changes to this file. C'est la vie.

Signed-off-by: Dave Cheney <dave@cheney.net>

Fixes #1377

BREAKING CHANGE

We build with -mod=readonly so that the build will fail if anything is
out of date in our go.mod file. golang/go#30667 changed the behaviour of
the go tool to require that go.mod AND go.sum be up to date so this
means I cannot use my hack of .gitignoring the go.sum file.

This means when you pull this commit you will probably have to delete
your local go.sum working copy. If we're lucky then you shouldn't need
to change it after that. If we're not lucky, the bloody thing will
always be dirty and we'll waste a lot of time telling people to revert
their changes to this file. C'est la vie.

Signed-off-by: Dave Cheney <dave@cheney.net>