Downgrade from XQuartz-2.7.1_rc2 to XQuartz-2.7.1_rc1 doesn't work

[tgl@…]

After encountering instability in rc2 (see ticket 538), I tried to reinstall rc1 over it. This did not work: XQuartz wouldn't launch anymore. I eventually resorted to manually trashing /Applications/Utilities/XQuartz and then running the rc1 installer, and now it seems okay.

Inspection of /var/log/system.log seems to tell the tale: it looks suspiciously like X11.bin wasn't downgraded:

Jan 29 12:54:33 pro [0x0-0x52a52a].org.macosforge.xquartz.X11[12950]: dyld: Library not loaded: /opt/X11/lib/libpixman-1.0.dylib
Jan 29 12:54:33 pro [0x0-0x52a52a].org.macosforge.xquartz.X11[12950]:   Referenced from: /Applications/Utilities/XQuartz.app/Contents/MacOS/X11.bin
Jan 29 12:54:33 pro [0x0-0x52a52a].org.macosforge.xquartz.X11[12950]:   Reason: Incompatible library version: X11.bin requires version 25.0.0 or later, but libpixman-1.0.dylib provides version 24.0.0
Jan 29 12:54:34 pro com.apple.launchd.peruser.501[148] ([0x0-0x52a52a].org.macosforge.xquartz.X11[12950]): Job appears to have crashed: Trace/BPT trap: 5
Jan 29 12:54:34 pro ReportCrash[12956]: Saved crash report for X11.bin[12950] version ??? (???) to /Users/tgl/Library/Logs/DiagnosticReports/X11.bin_2012-01-29-125434_pro.crash

although I'll attach the DiagnosticReports file for completeness.

[jeremyhu@…]

This is a bug in the installer or packagemaker (I'm not sure which). Either way, I've told it to allow downgrading, and it's not downgrading. You can probably inspect /var/log/install.log and notice that it says something to the effect of "Not installing Xquartz.app due to newer version present" ... that's what is causing this.

[jeremyhu@…]

I figured out a workaround for this, so the next version will allow downgrades (to it), but 2.7.0 through 2.7.1_rc2 can't be downgraded to.

The workaround is to delete XQuartz.app first.

[jeremyhu@…]

Dupe #532