hg implementation broken

[dmitshur]

If you look at the current CI build 559 of the latest master (https://travis-ci.org/sourcegraph/go-vcs/builds/365273607), it's failing mostly because of hg.

Go 1.4 build is failing to build the golang.org/x/crypto/poly1305 package. This is not a bug, because golang.org/x repos only maintain support for current stable and previous version of Go, and 1.4 is very old.

Go 1.5 build is successfully installing the hglib module:

$ sudo easy_install python-hglib
Searching for python-hglib
Reading https://pypi.python.org/simple/python-hglib/
Downloading https://pypi.python.org/packages/5a/c8/b8c95d3ee5d57c7961d918c16a09ebb8b3122a87e373bbda9f1f35769ff3/python-hglib-2.5.tar.gz#md5=1a0b708eec9275028ea91068c3bd2401
Best match: python-hglib 2.5
Processing python-hglib-2.5.tar.gz
Writing /tmp/easy_install-0BigtL/python-hglib-2.5/setup.cfg
Running python-hglib-2.5/setup.py -q bdist_egg --dist-dir /tmp/easy_install-0BigtL/python-hglib-2.5/egg-dist-tmp-4LPXFX
zip_safe flag not set; analyzing archive contents...
Moving python_hglib-2.5-py2.7.egg to /usr/local/lib/python2.7/dist-packages
Adding python-hglib 2.5 to easy-install.pth file

Installed /usr/local/lib/python2.7/dist-packages/python_hglib-2.5-py2.7.egg
Processing dependencies for python-hglib
Finished processing dependencies for python-hglib

But it's failing to use it:

--- FAIL: TestRepository_BlameFile (1.34s)
	blame_test.go:97: hg cmd: BlameFile(f, &{NewestCommit:63e47acf80095270f4e2b81e8cc01a89416c0cf3 OldestCommit: StartLine:0 EndLine:0}): EOF (stderr: Traceback (most recent call last):
		  File "<stdin>", line 92, in <module>
		  File "build/bdist.linux-x86_64/egg/hglib/client.py", line 390, in annotate
		  File "build/bdist.linux-x86_64/egg/hglib/client.py", line 261, in rawcommand
		hglib.error.CommandError: (255, 'f1f126ec4cf9: line1\n63e47acf8009: line2', 'abort: --: no such file in rev 63e47acf8009')
		)
--- FAIL: TestRepository_ResolveBranch (0.43s)
	repository_test.go:1846: hg.Open("/tmp/go-vcs-test/hg920022753") failed: .hg/requires: unknown requirement: generaldelta
--- FAIL: TestRepository_ResolveBranch_error (0.34s)
	repository_test.go:1846: hg.Open("/tmp/go-vcs-test/hg399928286") failed: .hg/requires: unknown requirement: generaldelta
--- FAIL: TestRepository_ResolveRevision (0.35s)
	repository_test.go:1846: hg.Open("/tmp/go-vcs-test/hg117032946") failed: .hg/requires: unknown requirement: generaldelta
--- FAIL: TestRepository_ResolveRevision_error (0.35s)
	repository_test.go:1846: hg.Open("/tmp/go-vcs-test/hg811635395") failed: .hg/requires: unknown requirement: generaldelta
--- FAIL: TestRepository_ResolveTag_error (0.35s)
	repository_test.go:1846: hg.Open("/tmp/go-vcs-test/hg842049905") failed: .hg/requires: unknown requirement: generaldelta
--- FAIL: TestRepository_ResolveTag (0.50s)
	repository_test.go:1846: hg.Open("/tmp/go-vcs-test/hg028952680") failed: .hg/requires: unknown requirement: generaldelta
--- FAIL: TestRepository_Branches (0.81s)
	repository_test.go:1846: hg.Open("/tmp/go-vcs-test/hg753804206") failed: .hg/requires: unknown requirement: generaldelta
--- FAIL: TestRepository_Tags (0.64s)
	repository_test.go:1846: hg.Open("/tmp/go-vcs-test/hg820735671") failed: .hg/requires: unknown requirement: generaldelta
--- FAIL: TestRepository_GetCommit (0.59s)
	repository_test.go:1846: hg.Open("/tmp/go-vcs-test/hg759776108") failed: .hg/requires: unknown requirement: generaldelta
--- FAIL: TestRepository_Commits (0.59s)
	repository_test.go:1846: hg.Open("/tmp/go-vcs-test/hg400518341") failed: .hg/requires: unknown requirement: generaldelta
--- FAIL: TestRepository_FileSystem_Symlinks (0.36s)
	repository_test.go:1846: hg.Open("/tmp/go-vcs-test/hg913714375") failed: .hg/requires: unknown requirement: generaldelta
--- FAIL: TestRepository_Commits_options (0.88s)
	repository_test.go:1846: hg.Open("/tmp/go-vcs-test/hg192693908") failed: .hg/requires: unknown requirement: generaldelta
--- FAIL: TestRepository_FileSystem (0.62s)
	repository_test.go:1846: hg.Open("/tmp/go-vcs-test/hg110844604") failed: .hg/requires: unknown requirement: generaldelta
--- FAIL: TestOpen (0.31s)
	repository_test.go:1631: Open("hg", "/tmp/go-vcs-test/hg929900531"): .hg/requires: unknown requirement: generaldelta
2018/04/11 19:11:06 parsing time "" as "Mon Jan 02 15:04:05 2006 -0700": cannot parse "" as "Mon"
FAIL
FAIL	sourcegraph.com/sourcegraph/go-vcs/vcs	9.546s

tip build is having the same issues as 1.5.

I'm going to send PR #103 that disables hg tests in CI because they're not passing (and the fix isn't trivial), so CI can pass for git which is working correctly.