From fa5143c722dab749de9305dbaa85d618b5758440 Mon Sep 17 00:00:00 2001
From: CHEIKH Chawki <chawki.cheikh008@gmail.com>
Date: Tue, 4 Dec 2018 16:14:23 +0100
Subject: [PATCH] Solve hg "abandoned transaction" issue

---
 src/libexpr/primops/fetchMercurial.cc | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/libexpr/primops/fetchMercurial.cc b/src/libexpr/primops/fetchMercurial.cc
index 97cda2458..66f49f374 100644
--- a/src/libexpr/primops/fetchMercurial.cc
+++ b/src/libexpr/primops/fetchMercurial.cc
@@ -93,7 +93,22 @@ HgInfo exportMercurial(ref<Store> store, const std::string & uri,
             Activity act(*logger, lvlTalkative, actUnknown, fmt("fetching Mercurial repository '%s'", uri));
 
             if (pathExists(cacheDir)) {
-                runProgram("hg", true, { "pull", "-R", cacheDir, "--", uri });
+                try {
+                    runProgram("hg", true, { "pull", "-R", cacheDir, "--", uri });
+                }
+                catch (ExecError & e){
+                    string transJournal = cacheDir + "/.hg/store/journal";
+                    /* hg throws "abandoned transaction" error only if this file exists */
+                    if (pathExists(transJournal))
+                    {
+                        runProgram("hg", true, { "recover", "-R", cacheDir });
+                        runProgram("hg", true, { "pull", "-R", cacheDir, "--", uri });
+                    }
+                    else 
+                    {
+                        throw ExecError(e.status, fmt("program hg '%1%' ", statusToString(e.status)));
+                    }
+                }
             } else {
                 createDirs(dirOf(cacheDir));
                 runProgram("hg", true, { "clone", "--noupdate", "--", uri, cacheDir });