Finally I was able to do the enormous paperwork (no, it is not that much) to switch my old 1024D key to a new 4096R one. I was a bit afraid that there might be something bad happening, but my fear was without any reason. After the RT bug was closed, I could upload and sent signed emails to mailing lists. So thanks alot to everyone involved.
old key, 0xD362B62A54B99890
pub 1024D/54B99890 2008-07-23
Key fingerprint = 36E2 EDDE C21F EC8F 77B8 7436 D362 B62A 54B9 9890
uid Thorsten Alteholz (...)
sub 4096g/622D94A8 2008-07-23
new key, 0xA459EC6715B0705F
pub 4096R/0xA459EC6715B0705F 2014-02-03
Schl.-Fingerabdruck = C74F 6AC9 E933 B306 7F52 F33F A459 EC67 15B0 705F
uid [ uneing.] Thorsten Alteholz (...)
sub 4096R/0xAE861AE7F39DF730 2014-02-03
Schl.-Fingerabdruck = B8E7 6074 5FF4 C707 1C77 870C AE86 1AE7 F39D F730
sub 4096R/0x96FCAC0D387B5847 2014-02-03
Schl.-Fingerabdruck = 6201 FBFF DBBD E078 22EA BB96 96FC AC0D 387B 5847