[PATCH 4 of 7 mergedriver] commands.summary: switch to mergestate.read()

[Siddharth Agarwal]

# HG changeset patch
# User Siddharth Agarwal <sid0 at fb.com>
# Date 1447798855 28800
#      Tue Nov 17 14:20:55 2015 -0800
# Node ID 1c3f6bcf4b99e8f368b54518287eae3e0ea0fb44
# Parent  5f1d5c34efb07bc255677ede7a9568a349f7481c
commands.summary: switch to mergestate.read()

See previous patch for why we're doing this.

We do this with a bit of care -- it would be bad form for 'hg summary' to abort
completely if we encounter an unsupported merge record. Instead just warn about
that and continue with the rest of the summary.

diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -6208,8 +6208,15 @@ def summary(ui, repo, **opts):
         if d in status.added:
             status.added.remove(d)
 
-    ms = mergemod.mergestate(repo)
-    unresolved = [f for f in ms if ms[f] == 'u']
+    try:
+        ms = mergemod.mergestate.read(repo)
+    except error.UnsupportedMergeRecords as e:
+        s = ' '.join(e.recordtypes)
+        ui.warn(
+            _('warning: merge state has unsupported record types: %s\n') % s)
+        unresolved = 0
+    else:
+        unresolved = [f for f in ms if ms[f] == 'u']
 
     subs = [s for s in ctx.substate if ctx.sub(s).dirty()]