Mozillabuild fixes

README.markdown

@@ -4,6 +4,11 @@ In order to set this up, clone this repository somewhere,
 run the `git submodule init` and then `git submodule update`
 command, and add your clone to $PATH.
 
+Some commands require `python2`. If using mozilla-build on windows, `python2`
+might be missing, but `python` exists and is actually python 2 (check by running
+`python -V`). On such case, you can create a copy of `python.exe` as `python2.exe`
+at the same location - probably at `<mozilla-build>/python/`.
+
 Many of these tools rely on a notion of your current branch's "upstream
 branch".  For example, `git push-to-try` pushes to try all patches in your
 current branch that aren't upstream.  See the `git-tracks` section below for

git-push-to-hg

@@ -1,6 +1,15 @@
 #!/bin/bash
 set -e
 
+if ! hash python2 2> /dev/null; then
+  echo "'python2' is required but not found. Aborting."
+  if hash python 2> /dev/null; then
+    echo "'python' found at '$(which python)'."
+    echo "If using mozilla-build, you can copy it to 'python2.exe' at the same location."
+    echo "See README.markdown for more information."
+  fi
+fi
+
 # Push some commits from git to the git-temp qqueue in a given hg repository.
 # Note that this nukes the git-temp qqueue, if it exists.
 #
@@ -16,7 +25,10 @@ if [[ $OSTYPE == "msys" ]]; then
   # based on cygwin (which uses "c:/somedir") - but markh *actually* sees
   # "c:/somedir\filename" - which upsets most $0 usage.
   # So fix it up and store the result in $this
-  this="/${this/:/}" # change "c:" to "/c/"
+  # git-for-windows 2+ uses the same convension as msys(1) in mozilla-build: /c/
+  if [[ ${this:1:1} == ":" ]]; then
+    this="/${this/:/}" # change e.g. "c:" to "/c"
+  fi
   this="${this/\\//}" # change "\" to "/"
 fi