plugins/xslt: fix memory leak on error path

Reported by Coverity as CID #1125165
core/legion: fix memory leak

Reported by Coverity as CID #1010086
plugins/python: fix memory leak

Reported by Coverity as CID #971056
plugins/xslt: fix compilation

After 594880fb4628ff2184582a5d569de6bdefc790b5
linux_ns: fix memory leak

Reported by Coverity as CID #971052.
core/subscription: fix memory leak

Reported by Coverity as CID #971040.
core/legion: fix memory leak

Reported by coverity as CID #971022.
Revert "yaml: fix memory leak"

This reverts commit ba3ac9ad0993a343434e78d3bd5a793d70827acd.

Since it looks like add_export_option does not copy the string we
shouldn't free it.
plugins/python: check return value of bind to unix

Reported by Coverity as CID #995784
Merge pull request #496 from xrmx/coverity2712

More Coverity fixes