Windows Tests Are All Flakey on git operations

[carolynvs]

I think this test may need some love, this is the first failure so we'll see if it happens again.

This only failed on AppVeyor, not Travis:

--- FAIL: TestGitSourceListVersionsNoHEAD (0.50s)
	vcs_source_test.go:582: Error on cloning git repo: unable to get repository: Cloning into 'C:\Users\appveyor\AppData\Local\Temp\1\gotest102557298\smcache\sources\file---C--Users-appveyor-AppData-Local-Temp-1-gotest102557298-repo'...
		error: git upload-pack: git-pack-objects died with error.
		fatal: early EOF
		: command failed: [git clone --recursive -v --progress file://C:/Users/appveyor/AppData/Local/Temp/1/gotest102557298/repo C:\Users\appveyor\AppData\Local\Temp\1\gotest102557298\smcache\sources\file---C--Users-appveyor-AppData-Local-Temp-1-gotest102557298-repo]: exit status 1

[carolynvs]

The windows tests are failing more often, always on git operations. Is it safe to run multiple concurrent git processes at the same time on Windows? This is happening often enough that we need to address it.

https://ci.appveyor.com/project/golang/dep/build/2429

--- FAIL: TestVCSVersion (2.43s)
	test.go:233: go standard error:
	test.go:234: # cd C:\Users\appveyor\AppData\Local\Temp\1\gotest050160048\src\github.com\sirupsen\logrus; git submodule update --init --recursive
		package github.com/sirupsen/logrus: exit status 1
		
	test.go:237: go [get github.com/sirupsen/logrus] failed unexpectedly: exit status 1
--- FAIL: TestMultiFetchThreadsafe (63.43s)
    --- FAIL: TestMultiFetchThreadsafe/first (0.00s)
        --- FAIL: TestMultiFetchThreadsafe/first/sync:3:gopkg.in/sdboyer/gpkt.v2 (0.26s)
        	manager_test.go:735: https://gopkg.in/sdboyer/gpkt.v2 does not exist in the local cache and fetching failed: unable to get repository: Cloning into 'C:\Users\appveyor\AppData\Local\Temp\1\smcache662811912\sources\https---gopkg.in-sdboyer-gpkt.v2'...
        		: command failed: [git clone --recursive -v --progress https://github.com/sdboyer/gpkt C:\Users\appveyor\AppData\Local\Temp\1\smcache662811912\sources\https---gopkg.in-sdboyer-gpkt.v2]: exit status 1

https://ci.appveyor.com/project/golang/dep/build/2439

--- FAIL: TestGitSourceListVersionsNoDupes (0.38s)
	vcs_source_test.go:627: Error on cloning git repo: unable to get repository: Cloning into 'C:\Users\appveyor\AppData\Local\Temp\1\smcache006789135\sources\https---git.luolix.top-carolynvs-deptest--importers'...
		: command failed: [git clone --recursive -v --progress https://github.com/carolynvs/deptest-importers C:\Users\appveyor\AppData\Local\Temp\1\smcache006789135\sources\https---git.luolix.top-carolynvs-deptest--importers]: exit status 1

https://ci.appveyor.com/project/golang/dep/build/2453

--- FAIL: TestVCSVersion (3.80s)
	test.go:233: go standard error:
	test.go:234: # cd .; git clone https://go.googlesource.com/crypto C:\Users\appveyor\AppData\Local\Temp\1\gotest453331345\src\golang.org\x\crypto
		Cloning into 'C:\Users\appveyor\AppData\Local\Temp\1\gotest453331345\src\golang.org\x\crypto'...
		package golang.org/x/crypto/ssh/terminal: exit status 1
		
	test.go:237: go [get github.com/sirupsen/logrus] failed unexpectedly: exit status 1
--- FAIL: TestGetInfoListVersionsOrdering (0.62s)
	manager_test.go:590: Unexpected error from GetInfoAt https://github.com/sdboyer/gpkt does not exist in the local cache and fetching failed: unable to get repository: Cloning into 'C:\Users\appveyor\AppData\Local\Temp\1\smcache444235753\sources\https---git.luolix.top-sdboyer-gpkt'...
		: command failed: [git clone --recursive -v --progress https://github.com/sdboyer/gpkt C:\Users\appveyor\AppData\Local\Temp\1\smcache444235753\sources\https---git.luolix.top-sdboyer-gpkt]: exit status 1

https://ci.appveyor.com/project/golang/dep/build/2454

--- FAIL: TestGetInfoListVersionsOrdering (0.50s)
	manager_test.go:590: Unexpected error from GetInfoAt https://github.com/sdboyer/gpkt does not exist in the local cache and fetching failed: unable to get repository: Cloning into 'C:\Users\appveyor\AppData\Local\Temp\1\smcache120125627\sources\https---git.luolix.top-sdboyer-gpkt'...
		: command failed: [git clone --recursive -v --progress https://github.com/sdboyer/gpkt C:\Users\appveyor\AppData\Local\Temp\1\smcache120125627\sources\https---git.luolix.top-sdboyer-gpkt]: exit status 1

[sdboyer]

yeah, that shit is kinda killing me. i've restarted appveyor builds on i don't even know how many PRs. ugh.

i was toying with the idea of just doing the damn local repo implementation, so that 99% of this stuff no longer need go over the network.