Rework Spack's Mercurial support (#3834)

* Add tests to mercurial package

* Add support for --insecure with mercurial fetching

* Install man pages and tab-completion scripts

* Add tests and latest version for all deps

* Flake8 fix

* Use certifi module to find CA certificate

* Flake8 fix

* Unset PYTHONPATH when running hg

* svn_fetch should use to svn-test, not hg-test

* Drop Python 3 support in Mercurial

Python 3 support is a work in progress and isn't currently
recommended:

https://www.mercurial-scm.org/wiki/SupportedPythonVersions

* Test both secure and insecure hg fetching

* Test both secure and insecure git and svn fetching

4 files changed, 59 insertions, 8 deletions

diff --git a/lib/spack/spack/fetch_strategy.py b/lib/spack/spack/fetch_strategy.py
index 38752b3fc1..855b2f9379 100644
--- a/lib/spack/spack/fetch_strategy.py
+++ b/lib/spack/spack/fetch_strategy.py
@@ -808,8 +808,17 @@ class HgFetchStrategy(VCSFetchStrategy):
 
     @property
     def hg(self):
+        """:returns: The hg executable
+        :rtype: Executable
+        """
         if not self._hg:
             self._hg = which('hg', required=True)
+
+            # When building PythonPackages, Spack automatically sets
+            # PYTHONPATH. This can interfere with hg, which is a Python
+            # script. Unset PYTHONPATH while running hg.
+            self._hg.add_default_env('PYTHONPATH', '')
+
         return self._hg
 
     @property
@@ -829,9 +838,15 @@ class HgFetchStrategy(VCSFetchStrategy):
             args.append('at revision %s' % self.revision)
         tty.msg("Trying to clone Mercurial repository:", self.url, *args)
 
-        args = ['clone', self.url]
+        args = ['clone']
+
+        if spack.insecure:
+            args.append('--insecure')
+
+        args.append(self.url)
+
         if self.revision:
-            args += ['-r', self.revision]
+            args.extend(['-r', self.revision])
 
         self.hg(*args)
 
diff --git a/lib/spack/spack/test/git_fetch.py b/lib/spack/spack/test/git_fetch.py
index 3bd998c5c2..ef531ef65f 100644
--- a/lib/spack/spack/test/git_fetch.py
+++ b/lib/spack/spack/test/git_fetch.py
@@ -37,8 +37,15 @@ def type_of_test(request):
     return request.param
 
 
+@pytest.fixture(params=[True, False])
+def secure(request):
+    """Attempt both secure and insecure fetching"""
+    return request.param
+
+
 def test_fetch(
         type_of_test,
+        secure,
         mock_git_repository,
         config,
         refresh_builtin_mock
@@ -62,7 +69,12 @@ def test_fetch(
     pkg.versions[ver('git')] = t.args
     # Enter the stage directory and check some properties
     with pkg.stage:
-        pkg.do_stage()
+        try:
+            spack.insecure = secure
+            pkg.do_stage()
+        finally:
+            spack.insecure = False
+
         assert h('HEAD') == h(t.revision)
 
         file_path = join_path(pkg.stage.source_path, t.file)
diff --git a/lib/spack/spack/test/hg_fetch.py b/lib/spack/spack/test/hg_fetch.py
index 71e4693c56..29a6eef561 100644
--- a/lib/spack/spack/test/hg_fetch.py
+++ b/lib/spack/spack/test/hg_fetch.py
@@ -37,8 +37,15 @@ def type_of_test(request):
     return request.param
 
 
+@pytest.fixture(params=[True, False])
+def secure(request):
+    """Attempt both secure and insecure fetching"""
+    return request.param
+
+
 def test_fetch(
         type_of_test,
+        secure,
         mock_hg_repository,
         config,
         refresh_builtin_mock
@@ -62,7 +69,12 @@ def test_fetch(
     pkg.versions[ver('hg')] = t.args
     # Enter the stage directory and check some properties
     with pkg.stage:
-        pkg.do_stage()
+        try:
+            spack.insecure = secure
+            pkg.do_stage()
+        finally:
+            spack.insecure = False
+
         assert h() == t.revision
 
         file_path = join_path(pkg.stage.source_path, t.file)
diff --git a/lib/spack/spack/test/svn_fetch.py b/lib/spack/spack/test/svn_fetch.py
index 962a150909..69d675fe3c 100644
--- a/lib/spack/spack/test/svn_fetch.py
+++ b/lib/spack/spack/test/svn_fetch.py
@@ -33,12 +33,19 @@ from spack.version import ver
 
 @pytest.fixture(params=['default', 'rev0'])
 def type_of_test(request):
-    """Returns one of the test type available for the mock_hg_repository"""
+    """Returns one of the test type available for the mock_svn_repository"""
+    return request.param
+
+
+@pytest.fixture(params=[True, False])
+def secure(request):
+    """Attempt both secure and insecure fetching"""
     return request.param
 
 
 def test_fetch(
         type_of_test,
+        secure,
         mock_svn_repository,
         config,
         refresh_builtin_mock
@@ -56,13 +63,18 @@ def test_fetch(
     t = mock_svn_repository.checks[type_of_test]
     h = mock_svn_repository.hash
     # Construct the package under test
-    spec = Spec('hg-test')
+    spec = Spec('svn-test')
     spec.concretize()
     pkg = spack.repo.get(spec, new=True)
-    pkg.versions[ver('hg')] = t.args
+    pkg.versions[ver('svn')] = t.args
     # Enter the stage directory and check some properties
     with pkg.stage:
-        pkg.do_stage()
+        try:
+            spack.insecure = secure
+            pkg.do_stage()
+        finally:
+            spack.insecure = False
+
         assert h() == t.revision
 
         file_path = join_path(pkg.stage.source_path, t.file)