User installation migrated onto itself

[Stephan Bergmann]

I wondered why <https://bugs.freedesktop.org/show_bug.cgi?id=46074> 
"FILEOPEN: No Recent Documents..." reportedly hits Mac and Windows users 
going from LO 3.4 to 3.5, when it should only hit in cases where the 
user installation is migrated (which happens on Linux when going from LO 
3.4 to 3.5, thanks to 
<http://cgit.freedesktop.org/libreoffice/core/commit/?id=9276f7d5740a28b342db2a9bcd8644ff2f4f5742> 
"fdo#32263" committed towards LO 3.5, fixing 
<https://bugs.freedesktop.org/show_bug.cgi?id=32263> "Config file 
location," which changed the user installation location on Linux from 
~/.libreoffice/3 to ~/.config/libreoffice/3).

So I dug a little deeper and noticed that, at least on Mac, the first 
start of LO 3.5 (or later) migrates any existing user installation in 
~/Library/Application Support/LibreOffice/3 onto itself.

This appears to be due to 
<http://cgit.freedesktop.org/libreoffice/core/commit/?id=6b522673373797bbf53d795d53e0ec45175a5d67> 
"default config location has changed, look in old config dir when 
migrating," committed towards LO 3.5, which added

   Libreoffice 3=libreoffice/3

to /org.openoffice.Setup/Migration/SupportedVersions/VersionIdentifiers. 
  On a case-insensitive file system (as is common for Mac and Windows), 
this causes MigrationImpl::findInstallation 
(desktop/source/migration/migration.cxx) to identify 
~/Library/Application Support/LibreOffice/3 (which would be used by both 
LO 3.4 and 3.5 just fine and without requiring any migration) as an old 
user installation at ~/Library/Application Support/libreoffice/3 that 
needs migration.

The migration happens only on the first start of LO 3.5, due to 
<http://cgit.freedesktop.org/libreoffice/core/commit/?id=995a87e5cf63fe1626245b62fef4aa71fa02dc94> 
"disable multiple migrations via MIGRATED stamp file."  I do not 
understand what propblem exactly that is supposed to solve.

And would it not be better anyway to only migrate an old user 
installation if the new user installation does not yet exist?  That 
should also fix the case-insensitivity problem on Mac and Windows 
leading to that dubious self-migration, I think.

Stephan