The Arduino IDE 1.5.3 introduced some new features, such as support latest board Yun, or introduces new libraries and samples. But I found it is too buggy to use.

1. Compile code against Arduino Nano fails due to parameter mcu passed to avrdude is missing.

Reason:
The issue seems caused because the new IDE merged the menu items for Nano board. But for some reason, the configuration haven’t been updated accordingly.

Workaround:
Choose Arduino Duemilanove and Diecimila instead of Arduino Nano. Nano uses same chip as Duemilanove(ATmega328) and Diecimila(ATmega168), but uses a different PCB design. So the binary should be compatible.

2. Compile String(100, DEC) throws ambiguous matching error

Reason:
The issue is caused because the API signature updated to String(*, unsigned char), but constants are still declared as int.

Workaround:
Add force cast DEC, HEX, BIN to byte instead of int.

I assigned a dedicated ssh key pair for github repos.
And I have associated the key pair with github correctly in ~/.ssh/config.
But each time when I try to access github repos via ssh, both read(such pull or fetch) or write(such as push), I will get a strange error:

key_read: uudecode [some SSH key code]
ssh-rsa [SSH key code]
failed

I tried a lot to fix the problem, and finally I solved the problem by delete the file ~/.ssh/known_hosts
I assume the problem might be caused that there is some invalid association cached in the file. So maybe you can solve the problem by removing the related entries instead of delete the whole file.