get mononoke green in github CI

Summary:
X-link: https://github.com/facebookincubator/zstrong/pull/1018

* test-cross-repo-mononoke-git-sot.t deleted, remove from exclusion list
* exclude flaky integration tests

changes done to make this easier:
 * python-click wasn't found in sapling dir, added package mappings for rpm and deb so that we can pick up the installed version
 * add a bit more info to the "unknown python exception" message from hg
 * reduce paths set by getdeps, no point listing non-existing dir, makes it easier to see what is happening

X-link: https://github.com/facebook/sapling/pull/974

Reviewed By: quark-zju

Differential Revision: D64827811

Pulled By: ahornby

fbshipit-source-id: 82b4fa224d8ce957ef85e5ecf1e220f71c93e6c4

build/fbcode_builder/getdeps/buildopts.py

@@ -304,12 +304,14 @@ class BuildOptions(object):
             is_direct_dep = (
                 manifest is not None and m.name in manifest.get_dependencies(ctx)
             )
-            self.add_prefix_to_env(
-                loader.get_project_install_dir(m),
-                env,
-                append=False,
-                is_direct_dep=is_direct_dep,
-            )
+            d = loader.get_project_install_dir(m)
+            if os.path.exists(d):
+                self.add_prefix_to_env(
+                    d,
+                    env,
+                    append=False,
+                    is_direct_dep=is_direct_dep,
+                )
 
         # Linux is always system openssl
         system_openssl = self.is_linux()