convert: improve support for unusual .gitmodules

Previously convert would throw an exception if it encountered a git commit with
a .gitmodules file that was malformed (i.e. was missing, but had submodule
files, or was malformed).

Instead of breaking the convert entirely, let's print error messages and move
on.

hgext/convert/git.py

@@ -7,7 +7,7 b''
 
 import os
 import subprocess
-from mercurial import util, config
+from mercurial import util, config, error
 from mercurial.node import hex, nullid
 from mercurial.i18n import _
 
@@ -185,9 +185,19 b' class convert_git(converter_source):'
     def retrievegitmodules(self, version):
         modules, ret = self.gitread("git show %s:%s" % (version, '.gitmodules'))
         if ret:
-            raise util.Abort(_('cannot read submodules config file in %s') %
-                             version)
-        self.parsegitmodules(modules)
+            # This can happen if a file is in the repo that has permissions
+            # 160000, but there is no .gitmodules file.
+            self.ui.warn(_("warning: cannot read submodules config file in "
+                           "%s\n") % version)
+            return
+
+        try:
+            self.parsegitmodules(modules)
+        except error.ParseError:
+            self.ui.warn(_("warning: unable to parse .gitmodules in %s\n")
+                         % version)
+            return
+
         for m in self.submodules:
             node, ret = self.gitread("git rev-parse %s:%s" % (version, m.path))
             if ret:

tests/test-convert-git.t

@@ -482,6 +482,39 b' test non-tab whitespace .gitmodules'
   $ rm -rf hg-repo6
   $ cd git-repo6
   $ git reset --hard 'HEAD^' > /dev/null
+
+test missing .gitmodules
+
+  $ git submodule add ../git-repo4 >/dev/null 2>/dev/null
+  $ git checkout HEAD .gitmodules
+  $ git rm .gitmodules
+  rm '.gitmodules'
+  $ git commit -m "remove .gitmodules" .gitmodules
+  [master *] remove .gitmodules (glob)
+   Author: nottest <[e-mail]>
+   1 file changed, 3 deletions(-)
+   delete mode 100644 .gitmodules
+  $ git commit -m "missing .gitmodules"
+  [master *] missing .gitmodules (glob)
+   Author: nottest <[e-mail]>
+   1 file changed, 1 insertion(+)
+   create mode 160000 git-repo4
+  $ cd ..
+  $ hg convert git-repo6 hg-repo6 --traceback
+  fatal: Path '.gitmodules' does not exist in '*' (glob)
+  initializing destination hg-repo6 repository
+  scanning source...
+  sorting...
+  converting...
+  2 addsubmodule
+  1 remove .gitmodules
+  0 missing .gitmodules
+  warning: cannot read submodules config file in * (glob)
+  updating bookmarks
+  $ rm -rf hg-repo6
+  $ cd git-repo6
+  $ rm -rf git-repo4
+  $ git reset --hard 'HEAD^^' > /dev/null
   $ cd ..
 
 test invalid splicemap1