util: adjust hgcmd() to handle frozen Mercurial on OS X Previously, 'hg serve -d' was trying to exec the bundled python executable, which failed with: Unknown option: -- usage: python [option] ... Try 'python -h'... abort: child process failed to start See the previous patch for details about the content of the various command variables. Note that unlike the previous patch here an application bundling Mercurial could set $HG in the environment to get the correct result, there isn't anything that a bundling application could do to get the correct result here. 'hg serve -d' now launches under TortoiseHg, and there is a process listed in the background, but a client process cannot connect to it for some reason, so more investigation is needed.