On some pair of files, "diff" reports a diff on identical lines.
See the attached archive. At line 1272 of "diff -u out1 out2":

@@ -137681,90 +138934,186 @@
 26659
 468
 462
-26946
+26946
+470
+814
+815
[...]

This chunk shouldn't contain:

-26946
+26946

There's the same problem without the "-u" option.

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Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)