Since the split of the git-perltools package out of git which happened in the 1.6 timeframe, some git tools (such as "git am", "git send-email" and "git-submodule") are no longer included in buildtools or the build appliance. This package needs to be added in both of those places.
Scratch the build appliance, that was already fixed in master by Jackie in the following commit: http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=b0bbdf29a1fea4ced697d216f298bb606af559d2 That probably ought to be backported as well though.
Fix was merged to master: http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=a957ff1dc4d084f4b7868359a508241f4af480f4 We now just need the backport to 1.7 of this and Jackie's fix linked above.
Backports have now been made to dizzy: http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?h=dizzy&id=63c0b4a44148035568e557661076cdcbdb6492d6 http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?h=dizzy&id=2658acef69a0665e4d77f1b08cafb032749d9ee6
Verified on 553c99d2e2943c20ad027a300df6e464ea641149 and 1.7.1 (6dd21a9f152a93e2df1178d7a5bd903d7edcf4be)