Comment # 2 on bug 1050558 from zhen ren

Quote from https://en.opensuse.org/openSUSE:Packaging_scriptlet_snippets

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The scripts support a special flag, -p which specifies the interPreter that
should be used to run the script (the default is /bin/sh). Sometimes the -p
option is used with no body in order to run a single command directly rather
than having to spawn a shell to invoke the programs (i.e. %post -p
/sbin/ldconfig). Note that this form requires that there be nothing but white
space (not even comments) until the next section begins. 
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