Bug#523986: apt: Confusing "malformed Release file" error for nonexistent repository components

[Tim Abbott <tabbott@MIT.EDU>]

Package: apt
Severity: normal
Version: 0.7.20.2
Tags: patch

If you have an invalid component name in your sources.list file, e.g. the 
"mainy" in:

deb http://http.us.debian.org/debian/ sid mainy

and then you do an "apt-get update", you get this confusing error message:

W: Failed to fetch http://http.us.debian.org/debian/dists/sid/Release 
Unable to find expected entry mainy/binary-i386/Packages in Meta-index 
file (malformed Release file?)

Suggesting that the problem is (1) "Failed to fetch" and (2) the result of 
a malformed Release file is very confusing here, given that the issue here 
is a problem with the local configuration, not the remote repository (and 
that a typo in sources.list is probably much more common than a malformed 
Release file).

I've looked at the code that generates this error, and it is clear from 
apt-pkg/algorithms.cc that "Failed to fetch" is printed for essentially 
any error in the "apt-get update" process.  This seems simply wrong; the 
best fix for this issue is probably to change the way the error string is 
generated to move the "Failed to fetch" into the individual error messages 
related to fetching, and have some other initial error string for errors 
related to parsing or finding required components.


As a short-term fix, I think it would be desireable to change 
apt-pkg/acquire-item.cc to replace the error message

"Unable to find expected entry  " + (*Target)->MetaKey + " in Meta-index file (malformed Release file?)";

with

"Fetched successfully, but expected entry " + (*Target)->MetaKey + " not 
found in Meta-index (misspelled, or Release file malformed?)"

so that the complete error message reads 

"W: Failed to fetch http://http.us.debian.org/debian/dists/sid/Release
Fetched successfully, but expected entry mainy/binary-i386/Packages not found in Meta-index (misspelled, or Release file malformed?)"

which I think is at least more clear.  I've attached a patch to do this 
simple improvement (though I'd prefer it if the broader problem were fixed 
instead).

	-Tim Abbott

=== modified file 'apt-pkg/acquire-item.cc'
--- old/apt-pkg/acquire-item.cc	2008-10-29 17:58:48 +0000
+++ new/apt-pkg/acquire-item.cc	2009-04-14 05:47:41 +0000
@@ -1055,8 +1055,8 @@
          if (!Record)
          {
             Status = StatAuthError;
-            ErrorText = "Unable to find expected entry  "
-               + (*Target)->MetaKey + " in Meta-index file (malformed Release file?)";
+	    ErrorText = "Fetched successfully, but expected entry " 
+               + (*Target)->MetaKey + " not found in Meta-index (misspelled, or Release file malformed?)";
             return;
          }
          ExpectedIndexHash = Record->Hash;