Reproduced on Windows XP, lp:inkscape/0.92.x rev. 15207, 14557.
Reproduced on Xubuntu 16.04, lp:inkscape rev. 15260.
Reproduced on Debian Jessie backports, Inkscape 0.92.1 r15371
When reopening a file with locked guides, the guides are seen as unlocked.
Steps to reproduce:
1) launch inkscape (0.92.x or trunk)
2) create a guide
3) lock the guide
4) save document
5) close and reopen the document (or use 'File > Revert')
-> The guide's origin is the "normal" one, and the guide is unlocked (it can be moved).
6) do something else (create a rectangle).
7) undo
-> The guide is now locked as expected.
Unrelated to bug #1634472 "Guides origin initially not rendered if guides hidden on load" (only after rev. 15492 or 15493), but rather related to the original lock guides feature (rev. 14512, see bug #170144).
Reproduced as described with lp:inkscape/0.92.x r15346 (on OS X 10.7.5).