# HG changeset patch
# User mpm@selenic.com
# Date 1117831396 28800
# Node ID ccbcc4d76f81c038e8d7801b6df8b2cd9fe72ec0
# Parent  1aaa49039a6b109d589db95cd64cd24cef3e4d05
fix bad assumption about uniqueness of file versions

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Hash: SHA1

fix bad assumption about uniqueness of file versions

Mercurial had assumed that a given file hash could show up in only one
changeset, and thus that the mapping from file revision to changeset
was 1-to-1. But if two people perform the same edit with the same
parents, we can get an identical hash in different changesets.

So we've got to loosen up our uniqueness checks in addgroup and in
verify.

manifest hash: 5462003241e7d071ffa1741b87a59f646c9988ed
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diff --git a/hg b/hg
--- a/hg
+++ b/hg
@@ -417,7 +417,6 @@ elif cmd == "verify":
             
         manifestchangeset[changes[0]] = n
         for f in changes[3]:
-            revisions += 1
             filelinkrevs.setdefault(f, []).append(i)
 
     ui.status("checking manifests\n")
@@ -468,6 +467,7 @@ elif cmd == "verify":
         fl = repo.file(f)
         nodes = { hg.nullid: 1 }
         for i in range(fl.count()):
+            revisions += 1
             n = fl.node(i)
 
             if n not in filenodes[f]:
@@ -505,10 +505,6 @@ elif cmd == "verify":
             nodes[n] = 1
 
         # cross-check
-        for flr in filelinkrevs[f]:
-            ui.warn("changeset rev %d not in %s\n" % (flr, f))
-            errors += 1
-            
         for node in filenodes[f]:
             ui.warn("node %s in manifests not in %s\n" % (hg.hex(n), f))
             errors += 1
diff --git a/mercurial/hg.py b/mercurial/hg.py
--- a/mercurial/hg.py
+++ b/mercurial/hg.py
@@ -814,7 +814,7 @@ class localrepository:
         # pull off the changeset group
         self.ui.status("adding changesets\n")
         co = self.changelog.tip()
-        cn = self.changelog.addgroup(getgroup(), csmap, tr)
+        cn = self.changelog.addgroup(getgroup(), csmap, tr, 1) # unique
         changesets = self.changelog.rev(cn) - self.changelog.rev(co)
 
         # pull off the manifest group
diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -433,7 +433,7 @@ class revlog:
 
         yield struct.pack(">l", 0)
 
-    def addgroup(self, revs, linkmapper, transaction):
+    def addgroup(self, revs, linkmapper, transaction, unique = 0):
         # given a set of deltas, add them to the revision log. the
         # first delta is against its parent, which should be in our
         # log, the rest are against the previous delta.
@@ -463,7 +463,10 @@ class revlog:
             node, p1, p2, cs = struct.unpack("20s20s20s20s", chunk[:80])
             link = linkmapper(cs)
             if node in self.nodemap:
-                raise "already have %s" % hex(node[:4])
+                # this can happen if two branches make the same change
+                if unique:
+                    raise "already have %s" % hex(node[:4])
+                continue
             delta = chunk[80:]
 
             if not chain: