subrepo: fix a crash when archiving an svn or git subrepo

Only hgsubrepos have a repository attribute.  This is pretty hacky, but probably
the best we can do on stable.  Pushing the lfstatus check down into the wrapper
for hgsubrepo (and dropping the check for lfstatus at the top of
`hgsubrepoarchive()`) resulted in various test failures because:

  1) hgsubrepoarchive isn't returning the number of files archived at the
     bottom, resulting in an error about += NoneType
  2) These copypasta archive wrappers don't use progress bars
  3) Largefiles are *not* currently archived when using extdiff (68822b7cdd01),
     but pushing this context manager down into the subrepo resulted in it
     apparently doing so (as evidenced by progress bars being dropped)

The other uses of `lfstatus()` are not in the substate processing loop, so they
shouldn't be an issue.

I initially put testcases in this test for largefiles-{on,off}, and it flagged
a bunch of exit code differences for `cat` and `diff`, so I backed that off.

Differential Revision: https://phab.mercurial-scm.org/D7714

hgext/largefiles/overrides.py

@@ -1208,7 +1208,16 b' def overridearchive('
             sub = ctx.workingsub(subpath)
             submatch = matchmod.subdirmatcher(subpath, match)
             subprefix = prefix + subpath + b'/'
-            with lfstatus(sub._repo):
+
+            # TODO: Only hgsubrepo instances have `_repo`, so figure out how to
+            # infer and possibly set lfstatus in hgsubrepoarchive.  That would
+            # allow only hgsubrepos to set this, instead of the current scheme
+            # where the parent sets this for the child.
+            with (
+                util.safehasattr(sub, '_repo')
+                and lfstatus(sub._repo)
+                or util.nullcontextmanager()
+            ):
                 sub.archive(archiver, subprefix, submatch)
 
     archiver.done()
@@ -1266,7 +1275,15 b' def hgsubrepoarchive(orig, repo, archive'
         sub = ctx.workingsub(subpath)
         submatch = matchmod.subdirmatcher(subpath, match)
         subprefix = prefix + subpath + b'/'
-        with lfstatus(sub._repo):
+        # TODO: Only hgsubrepo instances have `_repo`, so figure out how to
+        # infer and possibly set lfstatus at the top of this function.  That
+        # would allow only hgsubrepos to set this, instead of the current scheme
+        # where the parent sets this for the child.
+        with (
+            util.safehasattr(sub, '_repo')
+            and lfstatus(sub._repo)
+            or util.nullcontextmanager()
+        ):
             sub.archive(archiver, subprefix, submatch, decode)
 
 

tests/test-subrepo-git.t

@@ -376,6 +376,15 b' archive subrepos'
   a
   s/g
 
+  $ hg -R ../tc archive -S ../lf_archive.tgz --prefix '.' \
+  >       --config extensions.largefiles= 2>/dev/null
+  $ tar -tzf ../lf_archive.tgz | sort | grep -v pax_global_header
+  .hg_archival.txt
+  .hgsub
+  .hgsubstate
+  a
+  s/g
+
 create nested repo
 
   $ cd ..