Change current dir for go get swagger so it doesn't modify go.mod

[guillep2k]

This PR fixes the CI vendor problem by keeping go get from changing go.mod every time it downloads swagger. In a long conversation with @mrsdizzie and @techknowlogick it was established that this seems to be the culprit of the latest unintended vendor changes:

Makefile:
		GO111MODULE="on" $(GO) get -u github.com/go-swagger/go-swagger/cmd/swagger@v0.20.1; \

That produces changes in gitea's go.mod every time a new version of a golang library is released.

To work around that problem I've come with this solution, which is not perfect but could work until a better one comes up.

It works by executing $(GO) get outside gitea's directory, so it won't see/modify go.mod.

[typeless]

I am a bit confused about the issue. If the we already specify the exact version of go-swagger, wouldn't it just update the go.mod once if we have committed the change?

[guillep2k]

I am a bit confused about the issue. If the we already specify the exact version of go-swagger, wouldn't it just update the go.mod once if we have committed the change?

You have a point, but we're not using a binary release from go-swagger. It may be pointing to master in some of its dependencies.

[mrsdizzie]

See #8079 for an explanation of why current behavior causes these type of problems and should get a proper fix going forward

[typeless]

@guillep2k That sounds like a headache if a dependency could potentially have their dependencies inconstant even if the semantic version has been specified. I expected that the MVS rules of Go modules do not work that way.

[guillep2k]

@guillep2k That sounds like a headache if a dependency could potentially have their dependencies inconstant once the semantic version has been specified. I expected that the MVS rules of Go modules do not work that way.

@typeless You are right again. @mrsdizzie explained it better in #8079.

[lunny]

We just need go-swagger as a command line tool but not depends that on gitea runtime. go get have these two feature. download a library or a tool. I think where the problem is.

[codecov-io]

Codecov Report

Merging #8078 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #8078      +/-   ##
==========================================
- Coverage   41.78%   41.76%   -0.02%     
==========================================
  Files         481      481              
  Lines       64425    64425              
==========================================
- Hits        26919    26910       -9     
- Misses      34036    34046      +10     
+ Partials     3470     3469       -1

Impacted Files	Coverage Δ
models/unit.go	62.16% <0%> (-5.41%)	⬇️
models/repo_indexer.go	64.63% <0%> (-2.04%)	⬇️
modules/log/event.go	64.61% <0%> (-1.03%)	⬇️

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[lafriks]

Closing in favor of #8087