Special case dib-python in dib-lint

It seems that on Xenial, it does not take much to confuse "file" and
it's mime guessing such that it thinks some files are not python.

"package-installs-v2" is a good example, since it has an interpreter
"dib-python" that "file" doesn't know about, and no extension.  While
looking at this, I've added emacs vars here so it opens in python
mode.

Change-Id: I01994b08c5ad8987925f1eec4062f5b6ee72eb8f

bin/dib-lint

@@ -83,10 +83,15 @@ for i in $(find elements -type f   \
             error "$i is not executable"
         fi
 
-        # Ensure 4 spaces indent are used
-        if [[ "$(file -b -k --mime-type $i)" =~ "text/x-python" ]]; then
+        # run flake8 over python files.  note our "dib-python"
+        # interpreter can confuse the magic matching being done in
+        # "file" and make it think the file is not python;
+        # special-case it.
+        if [[ "$(file -b -k --mime-type $i)" =~ "text/x-python" ]] || \
+               [[ $firstline =~ "dib-python" ]]; then
             flake8 $i || error "$i failed flake8"
         else
+            # Ensure 4 spaces indent are used
             if ! excluded indent ; then
                 indent_regex='^\( \{4\}\)* \{1,3\}[^ ]'
                 if grep -q "$indent_regex" ${i}; then

elements/package-installs/bin/package-installs-v2

@@ -101,3 +101,8 @@ def main():
 
 if __name__ == '__main__':
     main()
+
+# Tell emacs to use python-mode
+# Local variables:
+# mode: python
+# End: