Bug#638063: libdigest-sha-perl: should set up divert of /usr/bin/shasum installed by perl

[Dominic Hargreaves]

Package: libdigest-sha-perl
Severity: normal
Version: 5.62-1

At the moment, on sid, /usr/bin/shasum from this package will not be
installed, since perl Replaces libdigest-sha-perl. This causes dpkg to
silently ignore /usr/bin/shasum from the package being replaced.

AFAIK, the reason for the Replaces entry in the perl package is to make
upgrades work smoothly when the versioned Conflicts comes into play
(by hinting the removal of the old libdigest-sha-perl). However, when
this isn't the case -- ie when libdigest-sha-perl provides a newer
version than Digest::SHA than the perl package -- such as unstable at the
moment, both perl and libdigest-sha-perl can co-exist.

This results in a situation where the newer Digest::SHA is used (owing
to @INC ordering) but the old /usr/bin/shasum is being used, which is
inconsistent and is probably not what the user expects, having installed
libdigest-sha-perl (note: I haven't checked how the functionality in the
two scripts compares, but there is the potential for future problems even
if they currently provide the same functionality).

The solution in this case is to divert the /usr/bin/shasum and its man
page, as provided by the perl package, out of the way, in preinst and
postinst. See libdevel-dprof-perl for an example.

-- 
Dominic Hargreaves | http://www.larted.org.uk/~dom/
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