# HG changeset patch
# User mpm@selenic.com
# Date 1119984122 28800
# Node ID 9f67222186bd8f2fed8b30afb405f203ef57edad
# Parent  7f3fc8fd427ea05971988a285beb2370ddb41294
Disallow merging of unrelated projects

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Disallow merging of unrelated projects

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diff --git a/mercurial/hg.py b/mercurial/hg.py
--- a/mercurial/hg.py
+++ b/mercurial/hg.py
@@ -917,6 +917,9 @@ class localrepository:
             if f in m:
                 raise RepoError("already have changeset " + short(f[:4]))
 
+        if fetch == [nullid]:
+            raise RepoError("unrelated repository")
+
         self.ui.note("adding new changesets starting at " +
                      " ".join([short(f) for f in fetch]) + "\n")