The attached patch goes in right now. It fixes the bug for me, but not for Bennet (see http://bugzilla.lyx.org/show_bug.cgi?id=2231). I don't know what happens in his case, but I know for sure what the problem is in my case and that this patch is the right fix.
Georg Log: * src/insets/insetgraphics.C (prepareFile): output correct file name of compressed files (bug 2231)
Index: src/insets/insetgraphics.C =================================================================== --- src/insets/insetgraphics.C (Revision 13594) +++ src/insets/insetgraphics.C (Arbeitskopie) @@ -595,10 +595,10 @@ string const InsetGraphics::prepareFile( // buffer. // "nice" means that the buffer is exported to LaTeX format but not // run through the LaTeX compiler. - string const output_file = os::external_path(runparams.nice ? + string output_file = os::external_path(runparams.nice ? params().filename.outputFilename(m_buffer->filePath()) : OnlyFilename(temp_file)); - string const source_file = runparams.nice ? orig_file : temp_file; + string source_file = runparams.nice ? orig_file : temp_file; string const tex_format = (runparams.flavor == OutputParams::LATEX) ? "latex" : "pdflatex"; @@ -638,6 +638,8 @@ string const InsetGraphics::prepareFile( } string const unzipped_temp_file = unzippedFileName(temp_file); + output_file = unzippedFileName(output_file); + source_file = unzippedFileName(source_file); if (compare_timestamps(unzipped_temp_file, temp_file) > 0) { // temp_file has been unzipped already and // orig_file has not changed in the meantime.